Christopher Lloyd

Controls on the location and geometry of glacial overdeepening

Supervisors: Professor Chris Clark (University of Sheffield), Dr Darrel Swift (University of Sheffield)

Publications

Lloyd, C.T., Clark, C.D. & Swift, D.A., 2012. Controls on the location and geometry of glacial overdeepening. Vienna, Austria, European Geosciences Union General Assembly.
Lloyd, C.T., 2011. Glacial overdeepening (Definition). In: V.P. Singh, P. Singh & U.K. Haritashya, eds. Encyclopedia of Snow, Ice and Glaciers. s.l.:Springer, p.358.
Lloyd, C.T., Clark, C.D. & Swift, D.A., 2010. Controls on the location of glacial overdeepening. Aberystwyth, U.K, International Glaciological Society British Branch 35th Annual Meeting, Aberystwyth University.

Clark, C.D., Lloyd, C.T. & Swift, D.A., 2011. Controls on the location of glacial overdeepening. Bern, Switzerland, XVIII INQUA-Congress.

Lloyd, C.T., 2008. The Impact of Windthrow on the carbon balance of a UK forest, Aberfoyle, Scotland. LiDAR research project: University of Edinburgh/ Forest Research, Forestry Commission, Edinburgh, UK (unpublished MSc dissertation).
Lloyd, C.T., 2003. An archaeo-geophysical investigation to locate the site of a former iron foundry, Madeley, Staffordshire, UK. Geophysics research project: University of Keele (unpublished MSci dissertation).

Qualifications

MSc (2008) Remote Sensing & Image Processing (University of Edinburgh)
MSci (Hons) (2003) GeoScience (University of Keele)

Membership of Learned Societies

Fellow of the Geological Society
Member of the British Society for Geomorphology

Research Summary

Glacial overdeepenings are a glacial erosional landform that have yet to be systematically studied. Overdeepening is an important glaciological and geomorphological process that has the potential to influence the response of ice masses to climatic changes. The study of this phenomenon will allow significant improvements to our knowledge of glacial systems and landscape evolution.

In this investigation we use GIS tools and various digital elevation models (DEMs) to study several hundred glacial overdeepenings in the Labrador province of Canada. The investigation analyses controls on overdeepening location and geometry, focusing on the influence of glacial confluence and geology. Our hypotheses propose that changes in glacial valley cross-sectional area will drive overdeepening formation, via influencing basal ice velocities; and that proximity to major geological fault-zones will subsequently drive change in overdeepening geometry, via influencing supply of basal ice debris.

Our analyses show that overdeepening appears to correlate strongly with glacial confluence and, importantly, the correlation is strongest where confluence-geometry indicates ice-flow speed-up. Further, we find that the magnitude of ice-flow speed-up correlates with overdeepening depth only for confluences situated in or near major geological fault-zones. Our findings therefore support the hypothesis that overdeepening can be initiated by an increase in ice velocity. Further, we conclude that overdeepening is most effective where fractured bedrock enables efficient quarrying.

The study also provides systematic data regarding the most significant global overdeepenings to occur within the limits of the Last Glacial Maximum (LGM), data which could subsequently be used as a test of numerical models of glacial erosion.

Contact Details

Address: Department of Geography, University of Sheffield, Winter Street, Sheffield, S10 2TN, United Kingdom
Fax: +44 (0)114 222 7907
Email: ggp08ctl@sheffield.ac.uk