1. Hydrogeologic framework and potentiometric surface of the Williamson Creek Aquifer "B" sand in the Fort Polk area, Vernon Parish, Louisiana, March 1997 Author/Creator: Geological Survey (U.S.), cartographer Publication/Creation: [Reston, Va.] : U.S. Department of the Interior, U.S. Geological Survey, 2001 Resource Type: Map Access & Availability: Loading