Departmental Research Projects
Land and sea-level changes around Britain
This project uses a wide range of field and analytical methods to reconstruct coastal environments over the last 18000 years and relate the sediments to sea level at the time of their formation. Field sites include much of the east coast of Enland, the Solway Firth and western Scotland and a databank of radiocarbon dated sea-level index points, initiated in 1980 and expanded as contributions to various International Geological Correlation Programme Projects.
First analyses, published 1987 and 1989, quantified the regional-scale pattern of uplift and subsidence around the North Sea and were followed, in the Journal of Quaternary Science for 1989, by the first analysis for 35 years to provide a quantitative estimate of current land uplift and subsidence in mainland Great Britain to be supported by both geological and oceanographic data. Significant advances in data quality and spatial cover followed over the next 10 years, culminating in the recent analysis (Shennan & Horton, 2002) that includes tidal range changes and anthropogenic-induced land subsidence.
Other analyses, Geophysical Journal International 1992, with an updated analysis in 1999, was the first from the United Kingdom to correlate the long-term geological trends and short-term tide gauge data, resulting in a quantitative estimate of the current absolute rate of sea-level rise. This indicated no evidence for an acceleration in the rate of rise, that could be expected to result from the enhanced greenhouse effect.
Recent work involves collaboration with geophysical modellers (Kurt Lambeck at ANU; Richard Peltier at Toronto, Glenn Milne at Durham) to expand and improve understanding of interactions between earth rheology, ice sheet histories and the global signals contained within the sea-level records from the UK.
In the near future I aim to make available some graphical illustrations that can be downloaded from this page.
Shennan, I., Hamilton, S., Hillier, C., and Woodroffe, S. (2005). A 16 000-year record of near-field relative sea-level changes, northwest Scotland, United Kingdom. Quaternary International 133-134, 95-106.
Shennan, I., and Horton, B. P. (2002). Holocene land- and sea-level changes in Great Britain. Journal of Quaternary Science 17, 511-526.
Shennan, I., Peltier, W. R., Drummond, R., and Horton, B. (2002). Global to local scale parameters determining relative sea-level changes and the post-glacial isostatic adjustment of Great Britain. Quaternary Science Reviews 21, 397-408.
Shennan, I., Lambeck, K., Horton, B. P., Innes, J. B., Lloyd, J. M., McArthur, J. J., Purcell, T., and Rutherford, M. M. (2000). Late Devensian and Holocene records of relative sea-level changes in northwest Scotland and their implications for glacio-hydro-isostatic modelling. Quaternary Science Reviews 19, 1103-1136.
Woodworth, P. L., Tsimplis, M. N., Flather, R. A., and Shennan, I. (1999). A review of the trends observed in British Isles mean sea level data measured by tide gauges. Geophysical Journal International 136, 651-670.