An inversion of the glacial geomorphological record provides an effective means to reconstruct former ice sheets at ice sheet-scale. The last Irish Ice Sheet has a long history of investigation, but its most basic properties are debated. Much previous research, based on an incremental development of knowledge through field observation of glacigenic landforms and deposits, has locally yielded high levels of detail but this detail is spatially fragmented across the former ice sheet bed. The evidence-base for ice sheet reconstruction is therefore patchy and incomplete, and its internal inconsistencies make an ice sheet reconstruction, via this approach, problematic. This thesis explores new opportunities for palaeo-glaciological reconstruction offered by remotely sensed data. Systematic glacial landform mapping has been conducted throughout Ireland from a variety of satellite imagery and digital elevation models, and yields new Glacial Maps for Ireland comprising >39,000 landforms. These landform maps are the building blocks for a palaeo-glaciological reconstruction of the ice sheet. Adopting a 'flowset' approach, the full population of landform data is summarised as discrete cartographic units - flowsets - and their spatial, temporal and glaciodynamic information is extracted. The flowset record, integrated with the wealth of evidence and dating constraints in the literature, stimulates a reconstruction describing seven broad stages of ice sheet history. These provide a framework for the evolution of the last Irish Ice Sheet. Key elements of the reconstruction confirm and extend an early advance from a British ice source, a maximum period likely dominated by large ice streams, fragmentation of the ice sheet into separate ice bodies during retreat, and final decay in western mountain groups. The pattern of ice sheet evolution is both asymmetric and asynchronous. A range of scales of ice sheet behaviour are observed, from first-order, fundamental changes in ice sheet geometry (centres of mass and ice flow structure) to more local-scale high-frequency fluctuations of ice flow patterns. This new model acts as a framework for continued investigation of the evolution of the Irish Ice Sheet, and the observed ice sheet behaviour demands further exploration of the sensitivities and role of ice sheets in the wider ice - climate system.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:489647 |
| Date | January 2008 |
| Creators | Greenwood, Sarah L. |
| Publisher | University of Sheffield |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://etheses.whiterose.ac.uk/14933/ |
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