Facies

Classification of discontinuities

Geologic map

Archaeology

Coal measures

Geology

Coal

Paleontology

Structural basin

Mathematics

Mining engineering

Geography

Mathematical analysis

Isopach map

Abstract:This map is one of a series that shows the regional characteristics of the Upper Elkhorn No. 3 coal zone. The maps were prepared as part of the U.S. Geological Survey's National Coal Assessment Program, which compiles regional maps and databases that provide a comprehensive assessment of the most important coal beds in the nation. The Upper Elkhorn No. 3 coal zone has been one of the leading producers in the state of Kentucky and, in some areas, contains very high-quality coal. The zone is composed of a number of distinct coal beds that merge in some areas to form mineable coal bodies. This architecture results in complex stratigraphic relationships over the extent of the coal. For the purpose of this assessment, the zone has been divided into two beds, the lower (3A) and upper (3B). This map represents the total coal thickness, minus partings, of the lower or main bed for the eastern Kentucky region. It is not a traditional isopach map, because the mineable bed is not composed of the same benches in all areas (Figs. 1-3). Discontinuities, delineated by facies boundaries on the map, indicate abrupt changes in thickness caused by splitting; discontinuities also occur between areas where entirely different beds in the Upper Elkhorn No. 3 zone are favored for mining. The lower bed (3A) is the main bed north of the Pine Mountain Overthrust Fault, where it is also known as the Van Lear or Tom Cooper coal. South of the Pine Mountain Overthrust Fault the lower bed, also known as the Kellioka or B seam, is less well developed compared to the upper bed, known as the Darby or C seam.

Total Coal Thickness of the Upper Elkhorn No. 3A Coal (Lower Bed) in Eastern Kentucky