1. Faculty of Science, Technology, Engineering and Mathematics, The Open UniversityWalton Hall, Milton Keynes MK7 6AA, UK
2. Department of Geology and Petroleum Geology, University of AberdeenMeston Building, Aberdeen AB24 3UE, UK
3. School of GeoSciences, University of Edinburgh, Grant InstituteThe King's Buildings, James Hutton Road, Edinburgh EH9 3FE, UK
4. School of Geography, Geology and the Environment, University of LeicesterUniversity Road, Leicester LE1 7RH, UK