1. Approximate location of the 10,000-milligram-per-liter dissolved-solids boundary in the Silurian and Devonian carbonate-rock aquifer, southwestern and northern Indiana Author/Creator: Geological Survey (U.S.), cartographer Publication/Creation: Reston, Virginia : U.S. Department of the Interior, U.S. Geological Survey, 1994 Resource Type: Map Access & Availability: Loading