Known and probable karst in Ohio, by Richard R. Pavey, Dennis N. Hull, C. Scott Brockman, Gregory A. Schumacher, David A. Stith, E. Mac Swinford, Donovan M. Powers, Terry L. Sole, Kim E. Vorbau, Kevin D. Kallini, Emily E. Evans, Ernie R. Slucher, and Robert G. Van Horn, 1999 (revised 2002). Scale 1:500,000 (1 inch equals about 8 miles). Preceded by DCMS-24. The map contains these data layers: County boundaries, karst geology, bedrock contacts, and a data layer that displays buffer zones near to the known and indicated karst features. These buffer zones are termed "probable karst areas," defined as areas within a half mile of known or indicated karst, and/or are areas underlain by carbonate or gypsiferous bedrock, with overbur-den of less than 20 feet of noncarbonate bedrock and/or unconsolidated material. A free page-size version is available for download at the Survey's Web site: www.OhioGeology.com.