1. School of Geographical and Earth Sciences University of Glasgow Glasgow UK
2. Department of Environmental Sciences Macquarie University North Ryde New South Wales Australia
3. Now at Department of Earth and Environmental Sciences University of Michigan Ann Arbor Michigan USA
4. Department of Earth Sciences and Engineering Imperial College London London UK
5. AMS Laboratory, Scottish Universities Environmental Research Centre University of Glasgow Glasgow UK
6. Geology Department and Rubenstein School of the Environment and Natural Resources University of Vermont Burlington Vermont USA