At last, it looks as if things might be stirring. Geologists and geomorphologists are apparently beginning to realise that it would not be a bad idea to know more about the glaciation of the Bristol Channel area -- and all credit to Phil Gibbard and Tom Spencer for creating a studentship at Cambridge for somebody to get stuck in on answering some of the problems highlighted on this blog. Let's hope they get a really good student (presumably starting in Oct 2015?) capable of getting us closer to a definitive chronology.
Graduate Research Opportunities, University of Cambridge
C112: Pleistocene glaciation of the Bristol Channel area: sedimentology, stratigraphy and geochronology (Lead Supervisor: Philip Gibbard, Geography)http://essdtp.esc.cam.ac.uk/programme/climate-theme/c112-pleistocene-glaciation-of-the-bristol-channel-area
Supervisors: Philip Gibbard (Geography), Tom Spencer (Geography)
Importance of the area of research:
Investigation of the Quaternary history of the Bristol Channel region is an important, yet neglected focus of research. Its critical position between S. Wales and the SW Peninsula means that it has been overriden by ice during at least two major glaciations, the ice advancing up the Bristol Channel from the at some time (so far undetermined) during the Pleistocene (Crampton 1966). This is confirmed by finds of Pembrokeshire and Irish Sea erratics in SE Wales in Quaternary sediments (Bevins and Donnelly, 1992). In addition, there has long been controversy about the presence or absence of glacial deposits in the Bristol/Somerset area (e.g. Kidson and Haynes 1972) and on the floor of the Channel itself. New data collected by the supervisors demonstrates that Lundy, at the Channel's western end, was glaciated from the NW during the last glacial cycle, yet the extent of this advance further east remains unestablished. The age of glaciations further east in the Bristol Channel remains unknown and controversial. The evolution of the Bristol Channel itself is only vaguely known. Its floor includes a deep channel of the River Severn and tributaries. The implications for the evolution of the River Severn drainage system are profound, particularly including the river's extension offshore. The results will cast new light on the evolution of this critically important region.
This project will rely on detailed reconstruction of the three-dimensional field mapping and reconstruction of the Quaternary and associated sediment sequences. Field investigation for ground truthing will be carried out from available exposures on land throughout the area. This will be supported by using remote sensing (involving satellite imagery and aerial photographs), borehole logs from both on shore and offshore (from the BGS and other archives), sediment analysis and the application of appropriate geochronological techniques (U-series to date cemented deposits in limestone areas, OSL to date sands, radiocarbon to date organic deposits).
Crampton, C.B., 1966. Certain effects of glaciation in the Vale of Glamorgan, South Wales. Journal of Glaciology 6, 261-266.
Hughes, P.D., Gibbard, P.L., Ehlers, J. 2013. Timing of glaciation during the last glacial cycle: Evaluating the concept of a global 'Last Glacial Maximum' (LGM). Earth-Science Reviews vol.125, pp.171–198.
Bevins, R.E., Donnelly, R., 1992. The Storrie Erratic Collection : a reappraisal of the status of the Pencoed ‘Older Drift’ and its significance for the Pleistocene of South Wales. Proceedings of the Geologists’ Association 103, 129-142.
Gibbard, P.L. & Clark, C.D. 2011 Chapter 7 - Pleistocene Glaciation Limits in Great Britain. p. 75-93. In: Ehlers, J., Gibbard, P.L. & Hughes, P.D. (eds) 2011 Quaternary Glaciations - Extent and Chronology - A Closer Look. Developments in Quaternary Science 15.pp. 75-93.
Kidson, C., Haynes, J.R. 1972. Glaciation in the Somerset Levels: the evidence of the Burtle Beds. Nature 239, 390-392.
Rolfe, C.J., Hughes, P.D., Fenton, C.R., Schnabel, C., Xu, S., Brown, A.G. 2012. Paired 10Be and 26Al exposure ages from Lundy: new evidence for the extent and timing of Devensian glaciation in the southern British Isles. Quaternary Science Reviews 43, 61-73.