Author Affiliations +
Thomas M. Keevin,1 Leo G. Nico,2 Donald C. Taphorn3
1U.S. Army Corps of Engineers, 1222 Spruce Street, St. Louis, Missouri 63103; E-mail: Keevintm@yahoo.com.
2U.S. Geological Survey, 7920 NW 71 Street, Gainesville, Florida 32653; E-mail: . lnico@usgs.gov
31822 N. Charles Street, Belleville, Illinois 62221; E-mail: . Taphorn@gmail.com