[1] Department of Geography, University of Durham, Science Laboratories, Durham, DH1 3LE, South Road
[2] Division of Geography, School of Natural and Environmental Sciences, Coventry University, Coventry, CV1 5FB, Priory Street
[3] Centre for Quaternary Research, Department of Geography, Royal Holloway, University of London, Egham, Surrey, TW20 0EX, Egham Hill,
[4] Department of Geology, University of Cardiff, Cardiff, CF1 3YE