Mine à déplacement de sommet

Mountaintop removal mining (MTR), also known as mountaintop mining (MTM), is a form of surface mining at the summit or summit ridge of a mountain. Coal seams are extracted from a mountain by removing the land, or overburden, above the seams. This process is considered to be safer compared to underground mining because the coal seams are accessed from above instead of underground. In the United States, this method of coal mining is conducted in the Appalachian Mountains in the eastern United States. Explosives are used to remove up to 400 vertical feet (120 m) of mountain to expose underlying coal seams. Excess rock and soil is dumped into nearby valleys, in what are called "holler fills" ("hollow fills") or "valley fills". The practice of MTM has been controversial. While there are economic benefits to this practice, there are also concerns for environmental and human health costs. Mountaintop removal mining (MTR), also known as mountaintop mining (MTM), is a form of surface mining that involves the topographical alteration and/or removal of a summit, hill, or ridge to access buried coal seams. The MTR process involves the removal of coal seams by first fully removing the overburden lying atop them, exposing the seams from above. This method differs from more traditional underground mining, where typically a narrow shaft is dug which allows miners to collect seams using various underground methods, while leaving the vast majority of the overburden undisturbed. The overburden from MTR is either placed back on the ridge, attempting to reflect the approximate original contour of the mountain, and/or is moved into neighboring valleys. When excess rock and soil containing mining byproducts are disposed into nearby valleys, the valleys are called "holler fills" or "valley fills". MTR in the United States is most often associated with the extraction of coal in the Appalachian Mountains. Google Earth Engine and Landsat imagery report the extent of newly mined land from 1985 to 2015 to be 2,900 km2.