Overburden thickness categories of Pocahontas No. 3 coal bed

This dataset is a polygon coverage of the thickness of the overburden of the Pocahontas No. 3 coal bed, in feet. It was produced by importing 1:100,000 (30-minute) and 1:24,000 scale (7.5-minute) digital elevation models (DEM) into ARC, and merging the lattices into one. The structure elevation grid for the Pocahontas No. 3 coal bed was subtracted from the surface elevation grid, creating overburden thickness. This grid was contoured within the known extent of the Pocahontas No. 3 coal bed into 200, 500, 1000, 2000, and 3000 foot lines. This vector file was imported to ARC. Polygon attributes include a code for the USGS overburden category (Coal Resource Classification of the U.S. Geological Survey, USGS, Circular 891). Coverage name [...]