The full programme book (PDF) - Royal Geographical Society

T5
BRITICE-CHRONO Transect 3: constraining the timing and style of British-Irish Ice
Sheet retreat of the eastern Irish Sea ice lobe
R.C. Chiverrell 1 *, M.J. Burke 1 , G.S.P. Thomas 1 , D.H. Roberts 2 , D.J.A. Evans 2 , M.
Bateman 3 , S. Livingstone 3 , G. Duller 4 , D. Fabel 5 , D. Small 5
1 School of Environmental Sciences, University of Liverpool, Liverpool
2 Department of Geography, Durham University, Durham DH1 3LE
3 Department of Geography, University of Sheffield, Sheffield S10 2TN
4 Department of Geography & Earth Sciences, Aberystwyth University, Aberystwyth, SY23 3DB
5 Department of Geographical and Earth Sciences, University of Glasgow, Glasgow, G12 8QQ
The aim of Transect 3 of the NERC funded consortium BRITICE-CHRONO is to establish
the timing and style of retreat of the British-Irish Ice Sheet (BIIS) from maximum limits in
the English Midlands. There are two components to this research. First, a marine
geological cruise scheduled to take place on the RRS James Cook in 2014 sampling
materials between Anglesey and the Isle of Man, and second, a programme of on-shore
field sampling for terrestrial cosmogenic nuclide (TCN) dating, optically–stimulated
luminescence (OSL) dating and radiocarbon dating. This poster focuses on the results, to
date, of the terrestrial component. Ice in the eastern Irish Sea and Cheshire/Shropshire
lowlands was sourced by ice flowing through the Solway Firth, from the Lake District and
Pennines. The dominant ice-sources were in Scotland, Lake District and a Ribble Valley
Glacier fed by the South Pennine Icecap. At the Last Glacial Maximum these coalesced
and ran south across the floor of the Eastern Irish Sea, then split with lobes extending 1)
W to SW merging with the West Irish Sea (WIS) Ice Stream between the Isle of Man (IoM)
and Anglesey and 2) SSE through Cheshire to maximum limits near Wolverhampton.
Comprehensive mapping of the landform record from Shropshire to Lancashire (Thomas
et al., unpublished), on the Isle of Man (Thomas et al., 2004) and in Cumbria (Livingstone
et al., 2009) allows division of the transect into discrete zone of ice marginal retreat.
Substantial moraine systems punctuate the landform sequence: e.g. Oswestry-
Whitchurch, Kirkham and Bride moraines amongst others. Sampling has sought to
constrain deglaciation south to north across some 330 km testing the various hypotheses:
(1) retreat of the ice lobe was punctuated by still-stands; (2) pace of retreat varied with
marginal conditions (terrestrial/subaqueous), with ice bed-slope. Eighteen samples for
TCN dating were collected from glacially-scoured bedrock of the mid-Cheshire and
Shropshire Permo-Triassic sandstone ridge, with others from the Isle of Man. These
samples are first CN dating of glacigenic surfaces for the Permo-Triass in Britain. Well
defined ice marginal contexts (17 sites) with thick sequences of glacial outwash spaced
through the retreat sequence have provided >50 OSL samples from glacifluvial and icemarginal,
shallow subaqueous deposits, principally outwash sandur and glacilacustrine
deltas exposed in sand and gravel quarries. These age estimates will form the basis for
Bayesian modelling to establish the timing and pattern of retreat of the east Irish Sea
glacier.
Keywords: BRITICE-CHRONO; British-Irish Ice Sheet; Irish Sea Ice Stream, Cheshire,
Shropshire; Lancashire; Cumbria; Isle of Man; deglaciation
Livingstone, S.J., Evans, D.J.A. and Ó Cofaigh, C. 2010. Re-advance of Scottish Ice into the Solway
Lowlands (Cumbria) during the Main Late Devensian deglaciation. Quaternary Science Reviews,
29(19-20), 2544-2570.
Thomas GSP, Chiverrell RC, Huddart D (2004) Ice-marginal depositional responses to readvance
episodes in the Late Devensian deglaciation of the Isle of Man. Quaternary Science Reviews vol 23
issue 1-2 pp 85-106