1. Department of Geosciences, Texas Tech University, Lubbock, TX 79409-1053, USA
2. Norwegian Geological Survey, Trondheim 7491, Norway
3. Department of Geology and Geophysics, University of Wyoming, Laramie, WY 82071, USA
4. Department of Earth Science, University of California, Santa Barbara, Santa Barbara, CA 93106-9630, USA
5. Department of Geosciences and Geography, University of Helsinki, Helsinki FI-00014, Finland
6. Department of Geology, Lone Star College System, The Woodlands, TX 77381, USA
7. Department of Geoscience, University of Wisconsin, Madison, WI 53706-1692, USA