Ribbed moraines in northern Manitoba, Canada: characteristics and preservation as part of a subglacial bed mosaic near the core regions of ice sheets

Trommelen, Michelle S.; Ross, Martin; Ismail, Ahmed

doi:10.1016/j.quascirev.2014.01.010

Cited by 29 publications

(27 citation statements)

References 75 publications

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“…The longest and most streamlined features are associated with relatively abundant sediment (Figure d). These simulations suggest that some transitions in bed form type that occur in close proximity [ Trommelen et al ., ] may be driven by differences in the thickness of sediment.…”

Section: Simulations and Discussionmentioning

confidence: 99%

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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Section: Simulations and Discussionmentioning

confidence: 99%

Subglacial bed form morphology controlled by ice speed and sediment thickness

Barchyn

Dowling

Stokes

et al. 2016

Geophysical Research Letters

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“…King et al . () suggested that this feature might be analogous to a drumlinised ribbed moraine (Dunlop and Clark, , Trommelen et al ., ). About 30 km downstream, where velocities exceeded 95 m a −1 , they observed several ‘drumlins of classical form’ with elongation ratios between 1:1.5 and 1:4 (King et al ., : p. 665).…”

Section: Geophysical Investigation Of the Geomorphology Beneath Modermentioning

confidence: 97%

“…They argued that ‘pristine’ ribbed moraines were preserved under cold‐based ice, but that other patches of ribbed moraine were partially to fully streamlined during a transition to warm‐based ice during deglaciation. Interestingly, their detailed study of till composition and dispersal under the Hayes Lobe (terrestrial ice stream) in NE Manitoba (Trommelen et al ., ) revealed the presence of sticky spots that were identifiable as islands of 0.2 to 4 km wide patches of till dominated by a local composition, but surrounded by a regional farther‐travelled till sheet. The cause of these inferred sticky spots is intriguing because they occur in an area of abundant warm‐based streamlined bedforms, but they are possibly related to variations in subglacial water pressure (Trommelen et al ., ).…”

Section: Identification and Characterisation Of The Beds Of Palaeo Icmentioning

confidence: 99%

Geomorphology under ice streams: Moving from form to process

Stokes

2017

Earth Surf Processes Landf

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Ice streams are integral components of an ice sheet's mass balance and directly impact on sea level. Their flow is governed by processes at the ice-bed interface which create landforms that, in turn, modulate ice stream dynamics through their influence on bed topography and basal shear stresses. Thus, ice stream geomorphology is critical to understanding and modelling ice streams and ice sheet dynamics. This paper reviews developments in our understanding of ice stream geomorphology from a historical perspective, with a focus on the extent to which studies of modern and palaeo-ice streams have converged to take us from a position of near-complete ignorance to a detailed understanding of their bed morphology. During the 1970s and 1980s, our knowledge was limited and largely gleaned from geophysical investigations of modern ice stream beds in Antarctica. Very few palaeo-ice streams had been identified with any confidence. During the 1990s, however, glacial geomorphologists began to recognise their distinctive geomorphology, which included distinct patterns of highly elongated mega-scale glacial lineations, ice stream shear margin moraines, and major sedimentary depocentres. However, studying relict features could say little about the time-scales over which this geomorphology evolved and under what glaciological conditions. This began to be addressed in the early 2000s, through continued efforts to scrutinise modern ice stream beds at higher resolution, but our current understanding of how landforms relate to processes remains subject to large uncertainties, particularly in relation to the mechanisms and time-scales of sediment erosion, transport and deposition, and how these lead to the growth and decay of subglacial bedforms. This represents the next key challenge and will require even closer cooperation between glaciology, glacial geomorphology, sedimentology, and numerical modelling, together with more sophisticated methods to quantify and analyse the anticipated growth of geomorphological data from beneath active ice streams.

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“…This work combines surficial geology mapping using aerial photography and field verification, till geochemistry sampling and palaeo-ice flow mapping derived from striae evidence and supplemented by landform mapping (e.g. Batterson & Taylor, 2009;Batterson, Taylor, Bell, Brushett, & Shaw, 2006;Brushett, 2012;Smith, 2012;Taylor, Bell, Brushett, & Shaw, 2009). Landform data collected as part of these regional mapping programmes are available from the Geoscience Atlas maintained by the Newfoundland and Labrador Department of Natural Resources.…”

Section: Glacial Landform Mapping In Newfoundlandmentioning

confidence: 99%

The subglacial imprint of the last Newfoundland Ice Sheet, Canada.

McHenry

Dunlop

2015

Journal of Maps

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The former Newfoundland Ice Sheet was situated on the fringes of the northeast Atlantic Ocean during the Wisconsinan glaciation ( 80-10 ka BP). Its geographic position indicates that it was likely to have been influenced by a number of external and internal forcing mechanisms including configuration changes in the Laurentide Ice Sheet with which it converged during the last glacial maximum, ice streams, changes in oceanic circulation and fluctuating sea levels. This makes Newfoundland a key location for investigating the dynamic response of ice sheets to these types of internal and external drivers. An established methodology for investigating ice sheet dynamics is to use the landform record to reconstruct the dynamic behaviour and configuration of the ice sheet. This provides a relative chronology of former ice sheet events during glacial cycles. A fundamental requirement of this approach is a detailed glacial geomorphology map that records the spatial distribution of individual subglacial bedforms across the former ice sheet bed. This paper presents a new subglacial bedform map of the Island of Newfoundland. It was produced as part of a mapping programme which used 10 m resolution Satellite Pour l'Observation de la Terre satellite imagery, Shuttle Radar Topography Mission and Canadian Digital Elevation Data. The map records the spatial distribution of 126,000 individually mapped glacial lineations and ribbed moraines and extends the number and spatial extent of each landform across the island. It is a new data set which has the potential to provide important insights into former ice sheet behaviour in this region.

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Ribbed moraines in northern Manitoba, Canada: characteristics and preservation as part of a subglacial bed mosaic near the core regions of ice sheets

Cited by 29 publications

References 75 publications

Subglacial bed form morphology controlled by ice speed and sediment thickness

Subglacial bed form morphology controlled by ice speed and sediment thickness

Geomorphology under ice streams: Moving from form to process

The subglacial imprint of the last Newfoundland Ice Sheet, Canada.

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