1. Department of Computer Sciences and Engineering Texas A&M University College Station TX 77843 USA
2. Graduate School of International Resource Science Akita University Akita 010‐8502 Japan
3. Department of Geology Lund University Lund 22362 Sweden
4. Department of Geosciences and Geography University of Helsinki Helsinki 00014 Finland
5. Geological Survey of Finland, Marine Geology Espoo 02151 Finland
6. School of Natural Science, Technology and Environmental Studies Södertörn University Huddinge SE‐141 89 Sweden