Coal in Ohio
Coal is found in the eastern third of Ohio within rocks of Pennsylvanian age (323–299 million years ago) and in the younger overlying rocks of Permian age (299–252 million years ago). The Pennsylvanian rocks of Ohio are divided into the following groups (oldest to youngest): Pottsville, Allegheny, Conemaugh, and Monongahela (click the map to enlarge). There are approximately 58 named coal seams of varying thickness in Ohio.
How Coal Forms
Coal is formed from the accumulation of undecayed plant material that once grew in swampy mires over long periods of time. Burial of this plant material under sedimentary rocks generates heat and pressure, which in turn causes physical and chemical changes to the plant material. The material is first transformed it into peat and then into coal. If these conditions are maintained, the plant material can build up and attain substantial thicknesses and form layers, which are called seams.
Coal Availability Mapping & Reports
Explore the links below to read recent coal availability studies. Or search our Publications Catalog.
- Evaluation of Available Resources of the Middle Kittanning (No. 6) and Lower Kittanning (No. 5) Coal Beds in Ohio (pdf)
- Evaluation of Available Resources of the Lower Freeport (No. 6a) Coal Bed in Ohio (pdf)
- Evaluation of Available Resources of the Pittsburgh (No. 8) Coal Bed in Ohio (pdf)
Coal Measurement & Elevation Data
The Division of Geological Survey manages a large collection of information on Ohio coals, including:
- Approximately 10,500 geophysical well logs.
- 4,000 measured stratigraphic-sections.
- 4,500 core descriptions.
- More than 600 individual physical and chemical analyses.
These records have been added to the National Coal Resources Data System (NCRDS), which is maintained by the U.S. Geological Survey and provides a platform to make these records publicly available.
Operator Reporting Forms
Download the publications below to learn more about Ohio coal geology. Or search our Publications Catalog.
- Educational Leaflet 8: Coal
- GeoFacts 14: History of Coal Mining in Ohio
- GeoFacts 15: Coal Mining and Reclamation
- GeoFacts 16: Coal and Electricity
- Bulletin 72: History of Coal-Mining Industry in Ohio
Learn more about Ohio coal production and economic information on our Industrial Minerals web page.