Geophysical Investigation of Ice Stream Bedforms (MSc or PhD)
Supervised by Dr Chris Stokes, Dr John Woodward (Northumbria University) & Dr Dave Roberts
Keywords: Ice Stream, Drumlins, Mega-Scale Glacial Lineations, Geophysics.
Given the importance of ice streams to ice sheet mass balance and concerns over their recent and future dynamics, it is becoming increasingly important to understand the subglacial processes that facilitate their flow and govern the rate at which both ice and sediment are discharged by ice sheets. Unfortunately, our understanding of the subglacial processes that generate the rapid velocity of ice streams is somewhat limited, but we do know that such processes create highly elongate subglacial bedforms (i.e. attenuated drumlins/mega-scale glacial lineations: e.g. King et al., 2007; 2009). Thus, constraining the formation of ice stream bedforms is likely to result in major advances in our understanding of the basal processes that act to sustain or inhibit ice stream flow.
Despite important advances in geophysical techniques on present-day ice streams, some of the most accessible ice stream bedforms are those produced (and since preserved) by ice steams from mid-latitude ice sheets during the last ice age (Stokes & Clark, 2001). Indeed, over the last decade or so, numerous workers have identified palaeo-ice streams tracks, largely based on the presence of highly elongate subglacial bedforms, despite the fact that there is little consensus as to how such bedforms are actually created. A part of the problem is that there are very few observations or data regarding the sub-surface structure of these bedforms, which is likely to provide important information about how they are created and, crucially, subglacial processes beneath ice streams.
The aim of this project, therefore, is to investigate subglacial bedforms on palaeo-ice stream beds using state-of-the art geophysical investigations of their sub-surface characteristics (e.g. using ground penetrating radar, seismic and electro-magnetic surveys, etc.) in conjunction with sedimentary evidence (e.g. coring, sediment exposures, etc.). Depending on funding, field-sites are likely to be in (but not restricted to) the UK, e.g. Tweed palaeo-ice stream (Everest et al., 2005) and the Solway lowlands (Livingstone et al., 2010). Candidates with knowledge and interests in glacial geomorphology/sedimentology are encouraged to apply. Training in geophysical techniques will be provided.
Everest, J., Bradwell, T. and Golledge, N. (2005) Subglacial landforms of the Tweed palaeo-ice stream. Scottish Geographical Journal, 121, 163-173.
King, E.C., Hindmarsh, R.C.A. and Stokes, C.R. (2009) Formation of mega-scale glacial lineations observed beneath a West Antarctic ice stream. Nature Geoscience, 2, 585-588.
King, E.C., Woodward, J., Smith, A.M. (2007) Seismic and radar observation of subglacial bed forms beneath the onset zone of Rutford Ice Stream, Antarctica. Journal of Glaciology, 53(183), 665-672.
Livingstone, S.J., Evans, D.J.A. and O’Cofaigh, C. (2010) Re-advance of Scottish ice into the Solway Lowlands (Cumbria, UK) during the Main Late Devensian deglaciation. Quaternary Science Reviews, 29, 2544-2570.
Pritchard, H.D., Arthern, R.J., Vaughan, D.G. and Edwards, L.A. (2009) Extensive dynamic thinning on the margins of the Greenland and Antarctic ice sheets. Nature, 461, 971-975.
Stokes, C.R., Spagnolo, M. and Clark, C.D. (2011) The composition and internal structure of drumlins: complexity, commonality, and implications for a unifying theory of their formation. Earth-Science Reviews, 107, 398-422.
Stokes, C.R. and Clark, C.D. (2001) Palaeo-ice streams. Quaternary Science Reviews, 20, 1437-1457.