1. Department of Geology and Geophysics, University of Utah, Salt Lake City, Utah 84112, United States
2. USDA-Agricultural Research Service, Environmentally Integrated Dairy Management Research Unit, 2615 Yellowstone Drive, Marshfield, Wisconsin 54449, United States
3. Department of Geology, University of Wisconsin Oshkosh, 800 Algoma Boulevard, Oshkosh, Wisconsin 54901-8649, United States