HR: 10:50h
AN: C52A-03    [Abstracts]
TI: Detailed Seafloor Evidence of Palaeo-ice Streaming Offshore N. Wales, UK: Implications for Decline of the Irish Sea Glacier
AU: * Van Landeghem, K J
EM: katrien.vanlandeghem@gmail.com
AF: Geology Department & Environmental Research Institute, University College Cork, Donovan's Rd., Cork, xxx, Ireland
AU: Wheeler, A
EM: a.wheeler@ucc.ie
AF: Geology Department & Environmental Research Institute, University College Cork, Donovan's Rd., Cork, xxx, Ireland
AU: Mitchell, N
EM: Neil.Mitchell@manchester.ac.uk
AF: School of Earth, Atmospheric and Environmental Sciences, University of Manchester, Williamson Building, Oxford Road, Manchester, M13 9PL, United Kingdom
AB: Recently acquired high resolution swath bathymetry data, 20 km offshore North Wales, UK reveal part of a glaciated terrain, unique in its kind on the European Shelf and provides the sole evidence for a grounded part of the Irish Sea Glacier. Exceptionally well-preserved ribbed moraines, drumlins, flutes, eskers, De Geer moraines and iceberg ploughmarks are all associated on a submarine landscape created in a subglacial and proglacial environment during times of final deglaciation of the Irish Sea. The shallow character of the till-bedrock interface offshore North Wales is enhanced by the presence of a major anticline in Carboniferous strata. In this setting, the spatial distribution and morphology of the observed ribbed moraines, drumlins, flutes and eskers can be explained using the time-space domain model for glacial bedform formation (Kleman and Hätterstrand, 1999). Spatial analysis of all the observed glacial features suggests a deglaciation mechanism for the grounded Irish Sea Glacier in the central and northern Irish Sea. It illustrates how a thawing front migrated up-glacier, drumlinising the subglacial bed, and halted at the edge of the ribbed moraine field close to where the anticline crops out. A quick and stepwise retreat of a grounded glacier followed, actively calving into a shallow proglacial water body. This water body then rapidly uplifted the glacier and almost simultaneously the subglacial terrain became ice free. This fast flooding prevented any terrestrial or coastal sediment from burying the glacial topography, allowing the glacial terrain to be beautifully preserved. Kleman, J., and Hätterstrand, C., 1999, Frozen-bed Fennoscandian and Laurentide ice sheets during the Last Glacial Maximum: Nature, v. 402, p. 63-66.
DE: 0720 Glaciers
DE: 0726 Ice sheets
DE: 0730 Ice streams
DE: 3045 Seafloor morphology, geology, and geophysics
SC: Cryosphere [C]
MN: 2007 Fall Meeting