1. Department of Earth and Env. Sciences Michigan State University East Lansing MI USA
2. Space Research Centre Polish Academy of Sciences Warsaw Poland
3. Laboratoire de Planétologie et Géodynamique de Nantes Université de Nantes, CNRS UMR6112 Nantes France
4. Géosciences Montpellier Université de Montpellier 2, CNRS UMR5243 Montpellier France
5. School of Earth Sciences Addis Ababa University Addis Ababa Ethiopia
6. Departments of Anthropology and Geological Sciences University of Texas at Austin Austin TX USA