This information helps in estimating how much more petroleum can be produced, on the basis of determinations of expulsion efficiencies of the source rock. Providing this type of information is part of the ongoing USGS National Petroleum Assessment. The USGS works closely with State agencies in acquiring the data necessary to make these calculations. The Nation depends on coal as a major source of energy. The use of coal is expected to increase during the next century to offset dependence on foreign oil and to sustain environmentally sound economic growth.
Coal mining has an important role in the economy of southern Indiana.
The effects of coal mining on stormflows and water quality have been studied in cooperative efforts between the USGS and the IDNR, Division of Water. The results of these studies have assisted resource managers in identifying and instituting responsible mining practices. As part of the cooperative geological mapping program, the USGS has partially funded and otherwise assisted the Indiana Geological Survey in the search for minable low-sulfur coal resources. The USGS also supports the Indiana mapping program with the identification of coal beds and associated horizons by means of analyses of their microfossil content. A key issue of interest to future users of coal is the quality of coal that will be mined in the next 20 years.