Bedrock Geology

In September 2006, the Division of Geological Survey achieved a major milestone by completing a  25-year program of remapping the bedrock geology of the state of Ohio. Beginning in 1990, the division sought to replace the 1920 bedrock geology map of the state. The Geologic Mapping Group produced the new map from 788 7.5-minute bedrock geologic quadrangles—an approach which distinguishes Ohio as one of only a few states to have complete bedrock map coverage at this scale. A more thorough discussion of mapping history and methods is included in the spring 1997 issue of Ohio Geology.

The resulting Bedrock Geologic Map of Ohio (Map BG-1) is a 1:500,000-scale, wall-size map, featuring a mosaic of colors, a correlation chart and descriptions of map units, and a detailed cross section that traces along a line from the Ohio River in Washington County to Bellefontaine to Williams County in the northwest corner of the state. As a testament to the hard work and quality put into Map BG-1, the division was honored by the Association of Earth Science Editors with a 2008 Outstanding Publication Award. Recently, the Bedrock Geologic Map of Ohio was made available in a page-size version and as a CD-ROM.

Provided below are links to further information on the Bedrock Geologic Map of Ohio and other bedrock geology products, including free downloads. For more specific questions about Ohio's bedrock geology, contact a staff geologist using our staff directory.

Bedrock Geology

• BG-1: Bedrock Geologic Map of Ohio
• Page-sized Bedrock Geologic Map of Ohio
  [3.9 MB PDF]
• Generalized Column of Bedrock Units in Ohio
  [123 KB PDF]
• The New Bedrock Geologic Map of Ohio, from Ohio Geology 2007, No. 1 [858 KB PDF]
• Remapping of the Bedrock Geology of Ohio Completed, from Ohio Geology Summer 1997 [522 KB PDF]

Bedrock Topography

• BG-3: Shaded Bedrock Topography Map of Ohio
• Page-sized Shaded Bedrock Topography Map of Ohio [4.7 MB PDF]
• Mapping Ohio's Hidden Landscape—The Shaded Bedrock-Topograpy Map of Ohio, from Ohio Geology 2003, No. 1 [790 KB]
• Bedrock Topography of Ohio, GeoFacts No. 1 [530 KB PDF]

Other Resources

• BG Digital Map Series—Bedrock geology, topography, and structure contour maps available in 1:500,00-scale; 1:100,000-scale; and 7.5-minute quadrangle, print-on-demand formats.
• OFR 98-1: Descriptions of Geologic Units—A compendium to accompany Division of Geological Survey open-file bedrock-geology maps. [136 KB PDF]
• OFR 98-2: Generalized Correlation Chart of Bedrock Units in Ohio
• 1:24,000-Scale Open-File Maps—Show bedrock geology and bedrock topography for the state of Ohio, originally drawn on Mylar copies of USGS 7.5-minute topographic maps. (Superseded by BG Digital Map Series products above.)
• Open-File County Bedrock Topography Maps

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