Debris entrainment and transfer in polythermal valley glaciers

H...............H

Show simple item record

dc.contributor.author Glasser, Neil F.
dc.contributor.author Hambrey, Michael J.
dc.contributor.author Dowdeswell, J. A.
dc.contributor.author Huddart, D.
dc.contributor.author Bennett, M. R.
dc.date.accessioned 2011-04-20T10:26:56Z
dc.date.available 2011-04-20T10:26:56Z
dc.date.issued 1999
dc.identifier.citation Glasser , N F , Hambrey , M J , Dowdeswell , J A , Huddart , D & Bennett , M R 1999 , ' Debris entrainment and transfer in polythermal valley glaciers ' Journal of Glaciology , pp. 69-86 . en
dc.identifier.issn 1727-5652
dc.identifier.other PURE: 158601
dc.identifier.other dspace: 2160/6675
dc.identifier.uri http://hdl.handle.net/2160/6675
dc.description Hambrey, MJ; Bennett, MR; Dowdeswell, JA, et al. (1999). Debris entrainment and transfer in polythermal valley glaciers. Journal of Glaciology, 45 (149), 69-86. Published: 1999 en
dc.description.abstract Modes of debris entrainment and subsequent transfer in seven 'normal' and five surge-type glaciers in Svalbard (76-79 degrees N) are outlined in the context of the structural evolution of a glacier as the ice deforms during flow Three main modes of entrainment and transfer are inferred from structural and sedimentological observations: (i) The incorporation of angular rockfall material within the stratified sequence of snow/firn/superimposed ice. This debris takes an englacial path through the glacier; becoming folded. At the margins and at the boundaries of flow units the stratified ice including debris is strongly folded, so that near the snout the debris emerges at the surface on the hinges and limbs of the folds, producing medial moraines which merge towards the snout. The resulting lines of debris are transmitted to the proglacial area in the form of regular trains of angular debris. (ii) Incorporation of debris of both supraglacial and basal character within longitudinal foliation. This is particularly evident at the surface of the glacier at the margins or at flow unit boundaries. It can be sometimes demonstrated that foliation is a product of strong folding, since it usually has an axial planar relationship with folded stratification. Foliation-parallel debris thus represents a more advanced stage of deformation than in (i). Although the presence of basal debris is problematic, it is proposed that this material is tightly folded ice derived from the bed in the manner of disharmonic folding. The readily deformed subglacial sediment or bedrock surface represents the plane of decollement. (iii) Thrusting, whereby debris-rich basal ice (including regelation ice) and subglacial sediments are uplifted into an englacial position, sometimes emerging at the ice surface. This material is much more variable in character than that derived from rockfalls, and reflects the substrate lithologies; diamicton with striated clasts and sandy gravels are the most common facies represented. Thrusting is a dynamic process, and in polythermal glaciers is probably linked mainly to the transition from sliding to frozen bed conditions. It is not therefore a solely ice-marginal or proglacial process. en
dc.format.extent 18 en
dc.language.iso eng
dc.relation.ispartof Journal of Glaciology en
dc.title Debris entrainment and transfer in polythermal valley glaciers en
dc.type Text en
dc.type.publicationtype Article (Journal) en
dc.contributor.institution Institute of Geography & Earth Sciences en
dc.contributor.institution Centre for Glaciology en
dc.description.status Peer reviewed en


Files in this item

Files Size Format View

There are no files associated with this item.

This item appears in the following Collection(s)

Show simple item record

Search Cadair


Advanced Search

Browse

My Account