From the site: "[L]inks to the digital coal resource shapefiles available from the ISGS Coal Section. The listed shapefiles are the same ones that were used to construct the County Coal Map Series maps and State Coal maps. These digital files have been reviewed and edited and meet the standards of the Illinois State Geological Survey with regard to scientific and technical quality and are suited to the purpose and the use intended by the ISGS Coal Section. They present reasonable interpretations of the geology of the area and are based on available data. However, the interpretations are based on data that may vary with respect to accuracy of geographic location, the type and quantity of data available at each location, and the reliability of the data sources. Consequently, the accuracy of unit boundaries and other features shown in these files varies from place to place. This data set provides a large-scale conceptual model of the geology of the area on which to base further work. Any map or cross section included herein is not intended for use in site-specific screening or decision-making. Use of this document does not eliminate the need for detailed studies to fully understand the geology of a specific site. The Illinois State Geological Survey and the University of Illinois make no guarantee, expressed or implied, regarding the correctness of the interpretations presented in this data set and accept no liability for the consequences of decisions made by others on the basis of the information presented here."

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