1. Institute of Geography Johannes Gutenberg‐University Mainz 55099 Mainz Germany
2. Institute of Geosciences Johannes Gutenberg‐University Mainz 55099 Mainz Germany
3. Department of Archaeology, Conservation and History University of Oslo 0371 Oslo Norway
4. State Key Laboratory of Loess and Quaternary Geology Institute of Earth Environment Chinese Academy of Sciences 710061 Xian China