Description of Area Portal 31 is located in Harlan County, near Lynch, Kentucky. The area lies within the Eastern Kentucky coal field which is divided into six separate coal districts. The Eastern Kentucky coal field is a hilly to mountainous region. Black Mountain, the highest point in Kentucky lies just to the south of Lynch at an elevation of 4139 feet above sea level. The topography of this area is steep with high ridges and low hollows.
Ridges are generally narrow and winding.
Natural flat land is mainly restricted to flood plains of major creeks and rivers. The Stratigraphic position of the mine site falls within the Breathitt Formation of Lower and Middle Pennsylvania Age. It is representative of rapid marine transgressions with intermittent, more gradual regressions while the sequence as a whole is regressive. Fluvial, deltaic and barrier systems are all represented within the Breathitt. This formation is characterized by rapid changes in lithology consisting of cyclic deposits of sandstone, siltstone, shale, and coal.