These images show shifting strip mines in eastern Ohio, from 1973 to 2013. In these images, the mines appear as pink or maroon against the bright green forest background.
The Muskingum mines were started in the 1950s in Muskingum County, Ohio, and are now operated by the American Electric Power Company. The bed of coal being mined, known as the Meigs Creek coal, is about 60 inches thick, of intermediate grade, and is part of the Monongahela geologic group, deposited about 300 million years ago.
At that time, central Ohio was covered by a shallow inland sea, with a floor of limestone and sandstone. Then, to the east, the Appalachian Mountains slowly pushed upward. Streams flowed off the mountains into this inland sea, dropping sediment and creating deltas along the coast in what is now eastern Ohio. Swamps grew on these deltas, and conditions were just right for the dying plants to form layers of peat. Over the years this peat was buried by more sediment (the sandstone and shale we now see covering the coal), transforming the peat into coal through heat and pressure.
Crowell, D.L., Wolfe, M.E., and Wickstrom, L., 2008, Coal—Educational Leaflet No. 8 (Rev. ed.): Ohio Geological Survey, 9 p. (Also available online at http://www.ohiodnr.com/Portals/10/pdf/EL/el08.pdf.)
Hansen, M.C., 1989, Guide to the Geology between Marietta and Cleveland along Interstate 77—Educational Leaflet No. 15: Ohio Department of Natural Resources, Division of Geological Survey, 1 p.
Larson, M.M., Olah, P., and Vimmerstedt, J.P., 1992, Forestation of Mined Lands—Effects of Soil Types and Seeded Herbaceous Species: Journal of Sustainable Forestry, v. 1, no. 1, p. 79–92.
Office of Surface Mining Reclamation and Enforcement, 1985, Public Law 95-87, The Surface Mining Control and Reclamation Act of 1977 (SMCRA): passed August 3, 1977 and all revisions through December 20, 2006, available online at http://www.osmre.gov/topic/smcra/smcra.shtm.
United States Department of Agriculture, Soil Conservation Service, 1985, Assessment and treatment of areas in Ohio impacted by abandoned mines: U.S. Dept. of Agriculture Soil Conservation Service.
Thanks to Gary Caster, forester for American Electric Power Company, and Dr. John Vimmerstedt, Ohio State University, for their assistance.