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Title: Reconstructing the Late Devensian (20 ka - 14 ka BP) deglaciation history of the southern Irish Sea basin : testing of competing hypotheses
Author: Rijsdijk, K. F.
Awarding Body: University of Wales Swansea
Current Institution: Swansea University
Date of Award: 2000
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There has been for more than 150 years controversy whether the southern part of the Irish Sea basin deglaciated under terrestrial or glacimarine conditions at the end of the last Ice Age (22 ka BP). The controversy is due to both a problematic interpretation of fossil glacial sediments - especially glacially diamicts - and the often purely inductive approaches taken in the past. In this thesis a deductive approach is formalised for the interpretation of fossil glacial sediments, based upon the testing of competing hypothesis and identification of exclusive process-based sedimentary criteria. Fossil glacial sediments are checked against the presence and absence of multiple criteria to test whether they were formed subglacially, as sediment-flows or by subaqueous rain-out. The sedimentologies of six fossil glacial successions of key-sites around the southern Irish Sea basin were investigated. Of all studied successions the sequence of depositional processes was reconstructed for each region. These findings, together with other published studies were synthesised in a model of land-system evolution during the Late Devensian deglaciation. It is demonstrated that there is no exclusive evidence for glacimarine deposition. Evidence is presented that sedimentary successions were formed by melting retreating terrestrial ice. It seems that the bulk of the glacial successions of the southern Irish Sea basin were laid down during the last ice-retreat, and for a major part comprised accumulations of ice-proximal and distal sediment flows. It is concluded that the southern Irish Sea basin was much less sensitive to the last glacial cycle as implied from the glacimarine hypothesis, sea-levels were not raised glaci-isostatically above the present margins and deglaciation was not triggered by seawater invading the basin from the south.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available