1. Geology Department, Macalester College, Saint Paul, Minnesota 55105, USA
2. Department of Earth Sciences, University of Minnesota, Minneapolis, Minnesota 55455, USA
3. Harold Hamm School of Geology and Geological Engineering, University of North Dakota, Grand Forks, North Dakota 58202, USA
4. University of Silesia in Katowice, Faculty of Earth Sciences, Będzińska 60, PL-41-200 Sosnowiec, Poland