These images show shifting strip mines in eastern Ohio, from the 1970s to the 1980s and 1990s. In these images, the mines appear as bright gray areas. Some of the reclaimed former mines are distinguishable from the surrounding vegetation by their darker red color.
Following the coal
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.1
Since their start in the 1950s, the mines have moved, following the coal deposits. In the zoomed-in 1973 image the mines appear in the northern part of the image. In the 1985, 1990, and 1997 images, the mines shift and change shape, generally moving south.
These images of the land's surface also give us clues about what lies underneath. The geology map of the area shows all the mine locations, in shades of green, on one image. Notice that almost all the mines lie within the orange areas. Orange represents the coal-bearing Monongahela group. In the red areas erosion long ago removed the coal, down to the limestone and sandstone underneath. In the yellow areas, coal remains but is covered by sandstone and shale.
Reclaiming the land
Federal Law requires the restoration of mined lands to their approximate original contours. It also requires that reclaimed land support either the same or better land uses than it supported before mining. To meet this requirement the Muskingum mines, as well as other mines, are replanted to grassland, for agricultural use. The mining company replaces the topsoil, grades the soil, and applies grass seed and mulch.2
The mining company is also planting some of this land to forest. As part of the voluntary Climate Challenge Program, the American Electric Power Company plans to plant 15 million trees on company-owned grassland. These new forests decrease the carbon dioxide in the atmosphere, control erosion, and provide habitat for wildlife.3
In the Landsat images, much of the reclaimed land is distinguishable from the surrounding forest. In the 1997 image, dark red areas can be seen where mines appeared in earlier years. This darker color results from higher visible-spectrum reflectivity and lower infrared reflectivity.
Question
The 1997 mines appear to lie in the yellow region on the geologic map. How can the mining company operate in an area of sandstone and shale?
(See the answer below.)
Footnotes
Thanks to Gary Caster, forester for American Electric Power Company, for his assistance with this article.
Thanks also to Dr. John Vimmerstedt of Ohio State University for his assistance with this article.
1. Horace R. Collins, 1988, Coal: Ohio Department of Natural Resources, Division of Geological Survey, Educational Leaflet No. 8. 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, v. 73, p.33. Michael C. Hansen, 1993, Guide to the Geology between Marietta and Cleveland along Interstate 77: Ohio Department of Natural Resources, Division of Geological Survey, Educational Leaflet No. 15.
2. United States Department of Agriculture, 1985, p. 34-35. Public Law 95-87, the Surface Mining Control and Reclamation Act of 1977 (SMCRA), passed August 3, 1977 and all revisions through December 31, 1993.
3. M. Larson, P. Olah, J. Vimmerstedt, 1993, Forestation of Mined Lands; Effects of Soil Types and Seeded Herbaceous Species: Journal of Sustainable Forestry, v. 1, p. 80.
LM1019032007324690 (Landsat 1 MSS, 3 September 1973)
LM5018032008519990 (Landsat 5 MSS, 18 July 1985)
LM5018032009022990 (Landsat 5 MSS, 17 August 1990)
LT5018032009718410 (Landsat 5 TM, 3 July 1997)
U.S. Geological Survey, 1972 (compiled 1967, revised 1972, printed 1976), Middle Atlantic States: National Atlas sheet 8-9, scale 1:2,000,000.
U.S. Geological Survey, 1988 (complied from USGS 1:100,000-scale maps dated 1980-1984), Clarksburg, WV-OH-PA: scale 1:250,000.
The rock layers in the geologic map were redrawn from Michael C. Hansen, 1993, Guide to the Geology between Marietta and Cleveland along Interstate 77: Ohio Department of Natural Resources, Division of Geological Survey, Educational Leaflet No. 15. The mines were drawn from the Landsat images.
The map of 300 million years ago is labeled "Middle Pennsylvanian Paleogeography" in Michael C. Hansen, 1993, Guide to the Geology between Marietta and Cleveland along Interstate 77: Ohio Department of Natural Resources, Division of Geological Survey, Educational Leaflet No. 15.
Photographs courtesy of Gary Caster, American Electric Power, McConnelsville, Ohio.
The sandstone and shale comprise the top rock layer in the yellow areas, but the layer underneath contains the Meigs Creek coal bed. The mining company removes the sandstone and shale to mine the coal underneath.
Campbell, Robert Wellman, ed. 1999. "Muskingum mines, Ohio: 1973, 1985, 1990, 1997." Earthshots: Satellite Images of Environmental Change. U.S. Geological Survey. http://earthshots.usgs.gov. This article was released 14 February 1999.
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