1. Institute of Geology and Mineralogy University of Cologne Zülpicher Str. 49a Köln D‐50674 Germany
2. Department of Earth Science University of Bergen Allégaten 41 5007 Bergen Norway
3. Department of Geography of Polar Regions Arctic and Antarctic Research Institute 38 Beringa st. St. Petersburg 199397 Russian Federation
4. Geomorphology Department Institute of Earth Sciences St. Petersburg State University 10 line V.O., 33 St. Petersburg 199178 Russian Federation