Coal is one of the world's primary energy sources and it is critical for making coke, used in steel making; and is used for a multitude of chemical products. Aside from its significance as a fuel or product, however, coal and data derived from the exploration or mining of coal have also provided the foundation and testing ground for diverse geologic concepts. Because of coal's economic importance, and common variability in thickness, distribution, and quality, it has been critical to collect and correlate a wide variety of surface and subsurface data sets at relatively high-spatial frequency, which varies from the mine to basinal scale. Also, because many coal beds occur in most coal basins, the collection of coal data from multiple beds creates relatively high-temporal frequency data sets at scales from laminae to bed to larger unit scale. These data have been important for the development and expansion of many earth science concepts including aspects of basin analyses, paleogeography, paleoclimatology, paleontology, stratigraphy, sedimentology, structural geology, and tectonics. (C) 2013 Elsevier B.V. All rights reserved.