1. Department of Earth and Environmental Sciences, Pavia University, Pavia, Italy
2. Council for Geoscience, Pietermaritzburg, South Africa
3. Department of Geography, Tübingen University, Tübingen, Germany
4. Department of Science and Mathematical Engineering, Faculty of Petroleum and Mining Engineering, Suez University, Suez, Egypt
5. Heidelberg Academy of Sciences and Humanities c/o, Tübingen University, Tübingen, Germany