The Ingredients for a Geomorphological Inversion of Landform Evidence to Reconstruct the Behaviour of the Last British-Irish Ice Sheet

Chris D Clark, Dave. J.A. Evans, P Dunlop, S.L. Greenwood, A.L.C. Hughs, G.R Bigg, C.J. Jordan, E Doyle

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Abstract

Reconstructing the extent, flow geometry and topography of former ice sheets has recently become more than an academic exercise because of the increasing perception of the importance of the cryosphere in producing change in the Earth-Ocean-Atmosphere system. Of particular note is the discovery that punctuated delivery of freshwater from ice sheets into the oceans (via icebergs and ice-dammed lakes) has the ability to significantly perturb the thermohaline circulation, and as a consequence force abrupt climate flips. The British-Irish Ice Sheet complex has been researched extensively over the last 150 years and the landscapes are rich with relevant data. However we are far from able to provide robust reconstructions on ice sheet extent, volume and changes therein. This paper reviews recent progress in compiling databases and information that can be used to build more complete reconstructions, and highlights new work utilising high resolution digital data (DEMs, satellite images, swath bathymetry) for landform mapping, both on- and off-shore.

Key ingredients for a full reconstruction include; the pattern of former ice flow from which ice divide positions can be established and ice streams identified; the overall pattern of ice retreat; offshore limits of the ice sheet (to the shelf edge? And confluence with Fennoscandian Ice Sheet?); vertical extent and hence ice thickness; and changes through time. An important objective is to deduce the time-integrated behaviour of the ice sheet and in particular any abrupt events such as ice streaming, break up of marine-sectors and drainage of large ice-dammed lakes. These latter points are to form the basis of numerical modelling experiments aimed at assessing the role (if any) of meltwater discharges from the BIIS in influencing the thermohaline circulation of the North Atlantic.

An extensive review of the literature has been made (Evans et al in press) from which pertinent data has been extracted and entered into a GIS to produce the BRITICE database and ‘Glacial Map of Britain’ (Clark et al, 2004). This has been used to identify inconsistencies and omissions in the information on moraines, eskers, drumlins, meltwater channels, ice-dammed lakes and erratic dispersal. This paper introduces the BRITICE database and reports on and illustrates recent work to add landform information to resolve inconsistencies and map new areas. Highlights will be presented of mega-scale glacial lineations and moraines on the Irish continental shelf, recording extensive ice cover here, ribbed moraines, drumlins and meltwater channels in Ireland and Britain, and the existence of large ice-dammed lakes.
Original languageEnglish
Number of pages1
Publication statusPublished - 26 Aug 2005
EventInternational Association of Sedimentologists: International Conference on Glacial Sedimentary Processes and Products - University of Wales, Aberystwyth, United Kingdom
Duration: 23 Aug 200527 Aug 2005

Conference

ConferenceInternational Association of Sedimentologists
Abbreviated titleIAS
CountryUnited Kingdom
CityAberystwyth
Period23/08/0527/08/05

Keywords

  • Ice sheet
  • landforms
  • glacial

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