Affiliation: | a Department of Geology, Brigham Young University, P.O. Box 24606, Provo, UT 84602-4606, USA;b Illinois State Geological Survey, 615 E. Peabody Drive, Champaign, IL 61820, USA;c Illinois State Geological Survey, 5776 Coal Drive, Carterville, IL 62918, USA;d Department of Geological Sciences, University of Kentucky, Lexington, KY 40506-0053, USA |