LiDAR-based quantitative assessment of drumlin to mega-scale glacial lineation continuums and flow of the paleo Seneca-Cayuga paleo-ice stream

Sookhan, Shane; Eyles, Nicholas; Bukhari, Syed; Paulen, R C

doi:10.1016/j.quascirev.2021.107003

Cited by 17 publications

(41 citation statements)

References 89 publications

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“…That subglacial bedforms are part of a morphological continuum (i.e., observation (iii) earlier), is supported and explained by our model results, which show that subglacial ribs can transition into drumlins over time, and during a period of bed smoothing, that drumlins can relax into MSGLs. This morphological transition has been observed to occur along palaeo‐ice stream tracks (ÓCofaigh et al, 2002; Hess & Briner, 2009; Sookhan et al, 2021) and has been modelled in Barchyn et al (2016). Notably, our modelling results never produce the opposite trajectory; drumlins never transition into subglacial ribs.…”

Section: Discussionmentioning

confidence: 76%

“…led us to consider three possibilities: (i) the herringbone patterns are MSGLs, but periodic boundary conditions cause them to become misaligned; (ii) we had not explored a conditions conducive to MSGL formation; and (iii) the model is unable to produce MSGLs in its current state. Observations of downstream transitions from drumlins to MSGLs (e.g.,ÓCofaigh et al, 2002;Sookhan et al, 2021), the morphological continuum between drumlins and MSGLs(Ely et al, 2016; …”

mentioning

confidence: 99%

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Numerical modelling of subglacial ribs, drumlins, herringbones, and mega‐scale glacial lineations reveals their developmental trajectories and transitions

Ely

Stevens

Clark

et al. 2023

Earth Surf Processes Landf

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Initially a matter of intellectual curiosity, but now important for understanding ice‐sheet dynamics, the formation of subglacial bedforms has been a subject of scientific enquiry for over a century. Here, we use a numerical model of the coupled flow of ice, water, and subglacial sediment to explore the formation of subglacial ribs (i.e., ribbed moraine), drumlins and mega‐scale glacial lineations (MSGLs). The model produces instabilities at the ice–bed interface, which result in landforms resembling subglacial ribs and drumlins. We find that a behavioural trajectory is present. Initially subglacial ribs form, which can either develop into fields of organized drumlins, or herringbone‐type structures misaligned with ice flow. We present potential examples of these misaligned bedforms in deglaciated landscapes, the presence of which means caution should be taken when interpreting cross‐cutting bedforms to reconstruct ice flow directions. Under unvarying ice flow parameters, MSGLs failed to appear in our experiments. However, drumlin fields can elongate into MSGLs in our model if low ice–bed coupling conditions are imposed. The conditions under which drumlins elongate into MSGLs are analogous to those found beneath contemporary ice streams, providing the first mechanism, rather than just an association, for linking MSGLs with ice stream flow. We conclude that the instability theory, as realized in this numerical model, is sufficient to explain the fundamental mechanics and process‐interactions that lead to the initiation of subglacial bedforms, the development of the distinctive types of bedform patterns, and their evolutionary trajectories. We therefore suggest that the first part of the longstanding ‘drumlin problem’ – how and why they come into existence – is now solved. However, much remains to be discovered regarding the exact sedimentary and hydrological processes involved.

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Section: Discussionmentioning

confidence: 76%

mentioning

confidence: 99%

Numerical modelling of subglacial ribs, drumlins, herringbones, and mega‐scale glacial lineations reveals their developmental trajectories and transitions

Ely

Stevens

Clark

et al. 2023

Earth Surf Processes Landf

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“…These sets can be traced southwards and matched with prominent finger‐like bulges in end moraines, such as the Lake Mills end moraine system (Figure 8), likely reflecting the presence of faster‐flowing (streaming) ice flow units along the lobe's axis. A similarly composite ice lobe structure, recorded by parallel but separate axial flow sets of MSGLs, was identified for the Seneca–Cayuga Ice Lobe in New York State (Sookhan et al, 2021). Overall, fast‐flowing ice was restricted to the lower‐lying axis of GBL moving over lower‐drag MSGLS (surfaces S5, S6) and channeled drumlins (surfaces S3, S4), flanked by less vigorous ice flowing over larger higher‐relief amplitude drumlinized surfaces (surfaces S1, S2) of higher frictional drag.…”

Section: Origins Of Morphotypes and Streamlined Surfacesmentioning

confidence: 76%

“…This study advances understanding of the origin of drumlins and MSGLs on the former bed of the Green Bay Lobe (GBL) in Wisconsin, USA, by presenting a quantitative methodology for mapping and classifying streamlined landforms (Figures 1–3). Sookhan et al (2021) used newly developed LiDAR‐based mapping techniques to map and quantitatively characterize the detailed form of drumlins across large areas of upper New York State. That study went well beyond conventional practice of separating bedforms into either drumlins or MSGLs based on consideration of elongation ratios, and used K ‐means clustering analysis to identify a statistically validated continuum of discrete bedform types between drumlins and MSGLs.…”

Section: Introductionmentioning

confidence: 99%

LiDAR‐based semi‐automated mapping of drumlins and mega‐scale glacial lineations of the Green Bay Lobe, Wisconsin, USA: Ice sheet beds as glaciotribological systems

Eyles

Bukhari

Sookhan

et al. 2022

Earth Surf Processes Landf

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A machine learning methodology for processing and visualizing high-resolution LiDAR digital data is used to map drumlins and mega-scale glacial lineations (MSGLs) on the bed of the Late Wisconsin Green Bay Lobe in Wisconsin, USA, which exhibited surge-like behaviour during deglaciation. Previous work has shown that streamlined bedforms are the product of erosional streamlining of pre-existing sediment. Analysis of bedform height and elongation ratio using curvature-based relief separation (CBRS) and K-means clustering of 32,003 bedforms reveals a continuum of six morphotypes ranging from drumlins, through "channeled" more elongated multi-crested drumlins, to MSGLs. Further statistical analysis shows that morphotypes cluster into six types of streamlined surfaces (S1-S6) recording progressive elimination of an antecedent overridden topography to produce a smoother bed. Initial, relatively high-relief drumlinized surfaces (S1, S2) occur around the slowerflowing lateral flanks of the lobe, where a pre-existing hummocky morainal topography was only partially modified by subglacial erosion. More streamlined surfaces (S3, S4) dominated by multi-crested more elongate drumlins of reduced relief amplitude are transitional to flow sets of MSGL-dominated surfaces (S5, S6) indicative of much faster-flowing ice streaming along the lobe's axis. Estimates of basal drag based on roughness calculations for each surface type identify a 61% reduction in frictional retardation from poorly streamlined surfaces S1 and S2 to MSGL-dominated surfaces S5 and S6, with a step-like reduction between drumlins and channeled drumlins (S3, S4) possibly recording the rapid onset of fast flow. Subglacial streamlining is argued to be accomplished by a thin (<1 m) "third layer" of deforming subglacial debris between ice and its bed which functioned as an erodent layer. A thin (<3 m) till cap, formed by aggradation of deforming debris, rests unconformably on heterogeneous core sediments. Streamlined subglacial surfaces are comparable to the "functional" surfaces resulting from erosion by a "third layer" of wear debris in engineering tribological systems, and also by gouge on faults. Pleistocene ice sheets expanded over pre-existing landsystems, pointing to the broader relevance of the methodology and findings reported here.

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“…Among the geomorphological features that may be identified in high‐resolution DEMs as indicators of former glaciations and ice flow directions are macroscale glacial striations, streamlined ridges such as drumlins, and roches moutonnées (e.g. Kelly et al ., 2004; Jansson and Glasser, 2005; Sookhan et al ., 2021).…”

Section: Methodsmentioning

confidence: 99%

LGM ice extent and deglaciation history in the Gurktal and Lavantal Alps (eastern European Alps): first constraints from ¹⁰Be surface exposure dating of glacially polished quartz veins

Wölfler

Hampel

Dielforder

et al. 2021

J Quaternary Science

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Compared with the western European Alps, the ice extent during the Last Glacial Maximum (LGM) and the subsequent deglaciation history of the eastern Alps east of the Tauern Window remain less well constrained. Also, considerable discrepancies exist between the mapped LGM ice margin and the ice extent predicted by ice-sheet models. Here we present the first 10 Be surface exposures ages from two regions east of the Tauern Window (the Gurktal and Lavantal Alps), which provide constraints on the LGM ice extent and the deglaciation history. Our results show that the deglaciation of the Gurktal Alps occurred between 16 and 14 ka, which agrees with the predictions from ice-sheet models. In contrast, the 10 Be ages from the Lavantal Alps located farther east are either LGM in age or predate the LGM, indicating that these regions were ice free or only partially covered by LGM ice. This finding suggests that ice-sheet models may have overestimated the LGM ice extent in the easternmost Alps. In conclusion, our study highlights the need for more age data from the eastern Alps to refine the location of the LGM ice margin and the deglaciation history, which is also crucial for climate-evolution and postglacial-rebound models.

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LiDAR-based quantitative assessment of drumlin to mega-scale glacial lineation continuums and flow of the paleo Seneca-Cayuga paleo-ice stream

Cited by 17 publications

References 89 publications

Numerical modelling of subglacial ribs, drumlins, herringbones, and mega‐scale glacial lineations reveals their developmental trajectories and transitions

Numerical modelling of subglacial ribs, drumlins, herringbones, and mega‐scale glacial lineations reveals their developmental trajectories and transitions

LiDAR‐based semi‐automated mapping of drumlins and mega‐scale glacial lineations of the Green Bay Lobe, Wisconsin, USA: Ice sheet beds as glaciotribological systems

LGM ice extent and deglaciation history in the Gurktal and Lavantal Alps (eastern European Alps): first constraints from ¹⁰Be surface exposure dating of glacially polished quartz veins

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LiDAR-based quantitative assessment of drumlin to mega-scale glacial lineation continuums and flow of the paleo Seneca-Cayuga paleo-ice stream

Cited by 17 publications

References 89 publications

Numerical modelling of subglacial ribs, drumlins, herringbones, and mega‐scale glacial lineations reveals their developmental trajectories and transitions

Numerical modelling of subglacial ribs, drumlins, herringbones, and mega‐scale glacial lineations reveals their developmental trajectories and transitions

LiDAR‐based semi‐automated mapping of drumlins and mega‐scale glacial lineations of the Green Bay Lobe, Wisconsin, USA: Ice sheet beds as glaciotribological systems

LGM ice extent and deglaciation history in the Gurktal and Lavantal Alps (eastern European Alps): first constraints from 10Be surface exposure dating of glacially polished quartz veins

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LGM ice extent and deglaciation history in the Gurktal and Lavantal Alps (eastern European Alps): first constraints from ¹⁰Be surface exposure dating of glacially polished quartz veins