1. Department of Geoscience, University of Wisconsin, 1215 West Dayton Street, Madison, WI 53706, USA
2. Wisconsin Geological and Natural History Survey, 3817 Mineral Point Rd, Madison, WI 53705, USA
3. Department of Civil and Environmental Engineering, University of Wisconsin, Water Science Engineering Laboratory, 660 N. Park Street, Madison, WI 53706, USA
4. Department of Geology, Beloit College, 700 College Street, Beloit, WI 53511, USA