Most of the coal mined in Indiana is surface mined. This means a large hole is dug to remove all of the soil and rock above the coal seam. In Indiana this will range from as little as 50 feet to as much as 150, even 200 feet. Once the coal is removed, all of the material is restored and the surface completely restored. Approximately 65 percent of Indiana coal is removed by surface mining.
Underground miningaccounts for the balance of extraction, or about 35 percent. An opening is cut in to the ground and a long entry formed down to the coal seam. All of the work is performed below ground and the coal brought to the surface by conveyor belts. Underground mines in Indiana usually range from 200 feet to over a thousand feet in depth.