Revised Ohio Karst Map Helps Homeowners, Developers And Land-use Planners Define Areas Of Possible Groundwater Pollution And Unstable Terrain

COLUMBUS, OH - The Ohio Department of Natural Resources (ODNR) Division of Geological Survey has released a revised and updated map of known and probable sinkholes, caves and caverns in the state. Collectively, these geologic features are known as karst.

The 2007 release of Known and Probable Karst in Ohio includes 57 newly documented sinkholes and caves. Karst is caused by the dissolution of limestone and dolomite bedrock and gypsum. Natural processes such as erosion and acidic rainwater cause the dissolution, resulting in networks of conduits below ground level and sinkholes and caves at the surface.

While karst can make interesting natural features, it can also rapidly transmit pollutants such as fertilizer runoff and sewage from leaky septic systems to water wells, streams and rivers. Unstable karst can also cause property loss and unexpected construction costs and delays.

Homeowners and planners involved with development, waste disposal, transportation, and water-related activities can use the new map to see if their general area of interest is a potential karst area. A half-mile radius is colored around each known karst feature on the map, indicating the probable location of more features.

A significant amount of limestone and dolomite bedrock (and to a lesser extent, gypsum) is present at or near the surface in western Ohio. Most of Ohio’s karst features are located in this region where soil and rock deposited by ancient glaciers is relatively thin and the bedrock is exposed to the forces of nature. Known karst features are also concentrated near the City of Bellevue in northern Ohio; in Highland and Adams counties in southern Ohio; and north of Columbus in central Ohio.

A component of the new map is colored shading that indicates glacial drift thickness. Boundaries of the Wisconsinan and Illinoian ancient glaciers were also added to the map to show the concentration of exposed limestone, dolomite, and gypsum in southern Ohio, beyond where the most recent glacial advance (the Wisconsinan) left drift 14,000 to 24,000 years ago.

The Known and Probable Karst in Ohio map contains text and figures that describe how karst forms and how research for the map was conducted. The wall-size Known and Probable Karst in Ohio (map EG-1) measures 50 inches by 35 inches and is available for $15; a CD version of the map is available for $25. Both versions can be ordered (tax and mailing fees apply) from the ODNR Geologic Records Center by calling 614-265-6576 or e-mailing ohiodnr.com/geosurvey. A free page-size version of the map is also available through the Publications, Maps and Data page of the ODNR Division of Geological Survey.

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For Further Information Contact:
Rick Pavey, ODNR Division of Geological Survey
(614) 265-6599
-or-
Jane Beathard, ODNR Media Relations
(614) 265-6860