1. Department of Zoology, Miami University, Oxford, Ohio 45056, Nordic Center for Earth Evolution, Institute of Biology, University of Southern Denmark, Campusvej 55, 5230 Odense M, Denmark, Environmental Chemistry and Technology Program, University of Wisconsin, 680 North Park Street, Madison, Wisconsin 53706, Department of Geology and Geophysics, University of Minnesota, 310 Pillsbury Drive SE, Minneapolis, Minnesota 55455, St. Croix Watershed Research Station, Science Museum of Minnesota, 16910 152nd...