In the past a series of reports on coal resources of selected counties in Indiana was published as part of the Special Report series of the Indiana Geological Survey (IGS). These reports included maps showing depth of the Springfield Coal Member (Petersburg Formation, Pennsylvanian). The depth maps were based on coal-test records, mine-map notations, and interpretations of geophysical logs that are included in the files of the Indiana Geological Survey. Different depth ranges were utilized in the various counties and for different purposes. Since 1980, staff members of the Indiana Geological Survey (IGS) have also collected and entered coal resource information into the NCRDS database as a cooperative project with the U.S. Geological Survey (USGS). The purpose of the NCRDS Database is to provide a means of rapid retrieval of point-source coal resource information, including coal location, thickness, depth, and other parameters. Based on all available data as of October 2010, a new map of Springfield Coal Member depth was created. It is the most current depth map of the Springfield Coal Member. Because additional data on coal depth are obtained by the Indiana Geological Survey on an annual basis, interested users may wish to contact the IGS for information on these more up-to-date sources.