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.
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 rest of the sequence of images, the mines shift and change shape, generally moving south.
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.
The mining company also planted some of this land to forest. As part of the voluntary Climate Challenge Program, the American Electric Power Company planted millions of trees on company-owned grassland. These new forests decrease the carbon dioxide in the atmosphere, control erosion, and provide habitat for wildlife.
In the Landsat images, much of the reclaimed land is distinguishable from the surrounding forest. Generally, bright pink is new mined land. As land is reclaimed, it turns darker and then becomes green as the vegetation returns.