Coal mining in the Appalachian Mountains has been happening for a long time. In fact, West Virginia is one of the largest coal producing states in the US and has been for decades. The process of mountain top/valley fill mining has been used in West Virginia in particular for removing coal deposits from the ground. Basically the upper ridge of a mountain chain is literally blasted with explosives and removed from the ground and the soil and rock are often placed in an adjacent valley. This exposes the coal buried under the former ridge for workers to remove and haul off. The economic benefits of this process are that it requires fewer workers and is faster than digging extensive tunnels under the ground. It also removes the risk of having underground mines collapse on workers.
The environmental impacts, however, are considerable. The process of removing a portion of the earth, even if it is backfilled with rock and soil, permanently alters the local landscape and reduces the biodiversity of the area. The visible scarring of the landscape can never be truly repaired. The discarded fill in the valleys also ultimately washes into area streams and rivers and increases the soil and mineral content of these waters, including drinking water. Finally, the extensive use of dynamite blasting expels dust and debris into the air and exposes the people and landforms to harmful, corrosive chemicals. So the environmental impact affects both wildlife and humans.