Glacial erosional landforms: origins and significance for palaeoglaciology

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dc.contributor.author Glasser, Neil F.
dc.contributor.author Bennett, Matthew R.
dc.date.accessioned 2009-12-22T15:11:59Z
dc.date.available 2009-12-22T15:11:59Z
dc.date.issued 2004
dc.identifier.citation Glasser , N F & Bennett , M R 2004 , ' Glacial erosional landforms: origins and significance for palaeoglaciology ' Progress in Physical Geography , vol 28 , no. 1 , pp. 43 . en
dc.identifier.issn 0309-1333
dc.identifier.other PURE: 142550
dc.identifier.other dspace: 2160/3894
dc.identifier.uri http://hdl.handle.net/2160/3894
dc.identifier.uri http://ppg.sagepub.com/cgi/content/short/28/1/43 en
dc.description Glasser, N. F., Bennett, M. R. (2004). Glacial erosional landforms: origins and significance for palaeoglaciology. Progress in Physical Geography 28, 1, pp. 43–75 en
dc.description.abstract Glacial inversion modelling of continental-scale palaeo-ice sheets is now recognized as an important tool in palaeoglaciology. Existing palaeoglaciological reconstructions of the dimensions, geometry and dynamics of former ice sheets are based mainly on glacial depositional, as opposed to glacial erosional, landforms. Part of the reason for this is a lack of detailed understanding of the origin and significance of glacial erosional landforms. Here we review recent developments in our understanding of the processes and landforms of glacial erosion and consider their value in palaeoglaciology. Glacial erosion involves the removal and transport of bedrock and/or sediment by glacial quarrying, glacial abrasion and glacial meltwater. These processes combine to create a suite of landforms that are frequently observed in areas formerly occupied by ice sheets and glaciers, and which can be used in palaeoglaciological reconstructions. For example, all landforms of glacial erosion provide evidence for the release of subglacial meltwater and the existence of warm-based ice. Landforms of glacial quarrying such as roches moutonnées, rock basins and zones of areal scouring are created when cavities form between an ice sheet and its bed and therefore are indicative of low effective basal pressures (0.1–1 MPa) and high sliding velocities that are necessary for ice–bed separation. Fluctuations in basal water pressure also play an important role in the formation of glacially quarried landforms. Landforms of glacial abrasion include streamlined bedrock features (‘whalebacks’), some ‘p-forms’, striae, grooves, micro-crag and tails, bedrock gouges and cracks. Abrasion can be achieved by bodies of subglacial sediment sliding over bedrock or by individual clasts contained within ice. Although abrasion models depend critically on whether clasts are treated as dependent or independent of subglacial water pressure, it appears that abrasion is favoured in situations where effective basal pressures are greater than 1 MPa and where there are low sliding velocities. Consequently, landforms dominated by glacial abrasion are created when there is no ice–bed separation. Landforms of glacial meltwater erosion include both subglacial and ice-marginal meltwater channels. Investigations of the relationship between glacial meltwater channels and other aspects of the subglacial drainage system, such as areas of ice–bed contact, areas of ice–bed separation and precipitate-filled depressions, enable inferences to be made concerning former subglacial water pressure-drainage relationships, effective pressures and glacier velocities. Meltwater palaeovelocity and palaeodischarge can also be calculated from measurements of channel shape, channel width and the size of material transported within former glacial meltwater channels. We surmize that glacial erosional landforms offer insight into former glaciological conditions at both the landform- and landscape-scale within palaeoglaciology. Exposureage dating techniques, including cosmogenic isotope dating of bedrock surfaces, will be important in increasing our understanding of the age and chronological significance of landforms of glacial erosion. We conclude that landforms of glacial erosion are of great value in ice mass reconstruction and speculate that these landforms will achieve greater recognition within palaeoglaciology in line with improvements in exposure-age dating techniques. en
dc.format.extent 43 en
dc.language.iso eng
dc.relation.ispartof Progress in Physical Geography en
dc.subject exposure-age dating en
dc.subject glacial erosional landforms en
dc.subject glacial erosional processes en
dc.subject palaeoglaciology en
dc.title Glacial erosional landforms: origins and significance for palaeoglaciology en
dc.type Text en
dc.type.publicationtype Article (Journal) en
dc.identifier.doi http://dx.doi.org/10.1191/0309133304pp401ra
dc.contributor.institution Institute of Geography & Earth Sciences en
dc.contributor.institution Centre for Glaciology en
dc.description.status Peer reviewed en


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