Calculating Quaternary glacial erosion rates in northeast Scotland

Glasser, Neil F.; Hall, Adrian M.

doi:10.1016/s0169-555x(97)00005-6

Cited by 45 publications

(40 citation statements)

References 51 publications

(55 reference statements)

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“…A similar scenario has been invoked for the Cairngorm Mountains in eastern Scotland (e.g. Sugden 1968;Glasser 1995;Glasser & Hall 1997;Phillips et al 2006). …”

Section: Altitude Of the Last Ice Sheetmentioning

confidence: 99%

The altitude of the last ice sheet in Caithness and east Sutherland, northern Scotland

Ballantyne

Hall

2008

SJG

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SynopsisOn the mountains of southern Caithness and east Sutherland, geomorphological evidence for the upper limit of glacial erosion implies that, at the last glacial maximum (LGM), warm-based erosive ice extended up to altitudes of 410-600 m. Above the upper limit of glacial erosion is a cover of frost-weathered detritus, with tors on conglomerate bedrock. Kaolinite and gibbsite in soils on such terrain imply that it escaped significant glacial erosion at the LGM. This is confirmed by cosmogenic 10 Be exposure ages of (>) 146.6 15.1 ka and (>) 178.2 18.1 ka obtained for summit tors; sites below the upper limit of glacial erosion yielded deglacial ages of 16.6 2.1 to 18.5 2.4 ka. It is unlikely that glacially unmodified summits represent LGM nunataks, as the implied ice thickness is inconsistent with an ice sheet that extended across high ground on Orkney onto the Atlantic shelf; under conservative assumptions at least 70 m of ice must have covered the highest ground in southern Caithness at the LGM. We infer that the absence of evidence for glacial erosion on some summits and plateaux reflects cover by cold-based ice, frozen to the underlying substrate, that preserved the underlying tors and blockfields. This inference calls into question the use of similar evidence in NW Scotland to identify the maximum altitude of the last ice sheet.

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“…A similar scenario has been invoked for the Cairngorm Mountains in eastern Scotland (e.g. Sugden 1968;Glasser 1995;Glasser & Hall 1997;Phillips et al 2006). …”

Section: Altitude Of the Last Ice Sheetmentioning

confidence: 99%

The altitude of the last ice sheet in Caithness and east Sutherland, northern Scotland

Ballantyne

Hall

2008

SJG

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“…Hence, our method has the potential to reconstruct the evolution of Quaternary relief over discrete glacial events by backfilling chronologically and volumetrically well-constrained erosional products found in adjacent sedimentary basins, in contrast to previous 'single step mass-balance studies' where the bulk of erosional products has been used to reconstruct pre-glacial relief (Braun, 1989;Nesje et al, 1992;Clayton, 1996;Glasser and Hall, 1997;Amato et al, 2003;Jamieson et al, 2005).…”

Section: Erosional Pattern Of the Riksgränsen Areamentioning

confidence: 98%

“…The amount of glacial erosion determined by a backfilling of offshore sediments (Braun, 1989;Vorren et al, 1991;Nesje et al, 1992;Clayton, 1996;Hjelstuen et al, 1996;Glasser and Hall, 1997;Elverhøi et al, 1998) or from a reconstructed pre-glacial surface is typically represented as a single erosional volume (Small and Anderson, 1998;Champagnac et al, 2007) or by estimates of surface lowering (Kleman and Stroeven, 1997;Lidmar-Bergström, 1997;Bonow et al, 2003Bonow et al, , 2006Lidmar-Bergström et al, 2007), rather than as a sequence of events. Because the impact of individual glacial episodes on relief production cannot be resolved in such studies, alternative approaches to landscape reconstruction are required to potentially constrain complex issues such as (i) glacial erosion patterns, processes, and rates, (ii) landscape evolution and palaeo-relief development over a glacial cycle scale, which can be used to constrain numerical ice sheet models, and (iii) the spatial pattern, magnitude and timing of mountain uplift in response to glacial erosion.…”

Section: Introductionmentioning

confidence: 99%

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Using a GIS filtering approach to replicate patterns of glacial erosion

Jansson

Stroeven

Alm

et al. 2010

Earth Surf Processes Landf

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Jansson, K. N., Stroeven, A. P., Alm, G., Dahlgren, K. I. T., Glasser, N. F., Goodfellow, B. W. (2011). Using a GIS filtering approach to replicate patterns of glacial erosion. Earth Surface Processes and Landforms, 36, (3), 408-418.In order to extend our knowledge of glacial relief production in mountainous areas new methods are required for landscape reconstructions on a temporal resolution of a glacial cycle and a spatial resolution that includes the most important terrain components. A generic data set and a 50 m resolution digital elevation model over a study area in northern Sweden and Norway (the present day landscape data set) were employed to portray spatial patterns of erosion by reconstructing the landscape over successive cycles of glacial erosion. A maximum-value geographic information system (GIS) filtering technique using variable neighbourhoods was applied such that existing highpoints in the landscape were used as erosional anchor points for the reconstruction of past landscape topography. An inherent assumption, therefore, is that the highest surfaces have experienced insignificant down-wearing over the Quaternary. Over multiple reconstruction cycles, proceeding backwards in time, the highest summits increase in area, valleys become shallower, and the valley pattern becomes increasingly simplified as large valleys become in-filled from the sides. The sum of these changes reduces relief. The pattern of glacial erosion, which is to 60% correlated to slope angle and to 70% correlated to relative relief, is characterized by (i) an abrupt erosional boundary below preserved summit areas, (ii) enhanced erosion in narrow valleys, (iii) restricted erosion of smooth areas, independently of elevation, (iv) eradication of small-scale irregularities, (v) restricted erosion on isolated hills in low-relief terrain, and (vi) a valley widening independent of valley directions. The method outlined in this paper shows how basic GIS filtering techniques can mimic some of the observed patterns of glacial erosion and thereby help deduce the key controls on the processes that govern large-scale landscape evolution beneath ice sheets. Copyright (C) 2010 John Wiley & Sons, Ltd.Peer reviewe

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“…Thaw of late-lying snow patches in recent warm summers has revealed 2-6 m of regolith, comprising occasional core stones in a matrix of sandy granular gravel and blocks (Figure 9). Previous suggestions (Ballantyne and Harris, 1994;Glasser and Hall, 1997) that the Cairngorm plateau supported a widespread cover of sandy weathered rock 10-20 m deep before glaciation are probably in error. Extensive cliff exposures show instead that unweathered granite extends close to the present landsurface except in narrow fracture zones.…”

Section: Plateau Regolithmentioning

confidence: 99%