1. Center for Coastal and Ocean Mapping/Joint Hydrographic Center; University of New Hampshire; Durham New Hampshire 03824 USA
2. Department of Geology and Geochemistry; Stockholm University; S-106 91 Stockholm Sweden
3. The Nordic Laboratory for Luminescence Dating, Department of Earth Sciences; University of Aarhus, RisøNational Laboratory; DK-4000 Roskilde Denmark
4. Institute of Solid Earth Physics, Allégt. 41; N-5007 Bergen Norway