Prairie Research Institute

Illinois State Geological Survey

Coal geology

About 201,000 acres of residential and other built-up land lie close to Illinois’ approximately 5,500 underground coal mines. ISGS offers an online Coal Mines in Illinois Viewer (ILMINES) to help home and business owners determine the proximity of coal mines and underground industrial mines to their properties. Although subsidence is uncommon, this tool helps landowners understand their risk.

Bedrock geology

ISGS bedrock geologists aid in the exploration of mineral resources and environmental studies. Our staff collects, analyzes, archives, and disseminates geologic information to aid in the exploration of mineral resources, including groundwater, petroleum, natural gas, coal, and metallic and industrial minerals, and also to aid in environmental studies, including earthquake hazards, groundwater protection, evaluation of selected construction sites, and disposal of various types of waste materials.

ISGS’s bedrock geologic mapping program investigates and reports on the pre-Quaternary geologic history of Illinois with an emphasis on sedimentary and crustal processes.


Stratigraphy is the study of major and minor natural divisions of rocks, particularly their form, arrangement, geographic distribution, chronologic succession, classification, correlation, and mutual relationships of rock strata. To learn more about the stratigraphy of Illinois, see the Online Handbook of Illinois Stratigraphy (ILSTRAT).

Geologic Samples Library

The Geological Samples Library is the legislatively mandated repository for drill-hole samples in Illinois, including cores drilled for mineral exploration and geologic investigations. The library also houses collections from mines, quarries, outcrops, clay pits, sand and gravel deposits, and more.

Industrial minerals

The Industrial Minerals and Resource Economics (IMRE) section provides geological, mineralogical, and economic research and service to the public, industry, and government agencies. Specific responsibilities of personnel in the Industrial Minerals section include:

  • mapping and characterizing the geology of Illinois’s nonfuel mineral resources to aid private individuals, industry, and government agencies
  • identifying high-quality, low-cost mineral resources that can be preserved and used through wise land-use planning
  • providing economic and policy information for Illinois’ geological resources.


Illinois’ aggregate resources occur in a wide variety of geological settings, from limestone and dolomite bedrock units of differing age to sand-and-gravel deposits formed in diverse river, beach, and glacial settings. The aggregate program:

  • inventories aggregate resources as part of the state’s geological mapping program
  • provides service to Illinois’ aggregate producers and the public using the latest geological research and historical information
  • investigates the feasibility of underground mining and the secondary use of mined-out space
  • maintains a database of existing and abandoned pits and quarries
  • provides mineralogical and geochemical information
  • assists producers in better use of existing resources and locating new sources
  • maintains a repository of data for the characterization of Illinois aggregate resources for present and future exploration
  • compiles information about Illinois mineral production and value and assists industry and the public in estimating reserves and value.

The aggregate program inventories these resources. Construction aggregates have low unit values per ton, but large tonnages of the material are needed for most construction purposes. 

Critical minerals

The U.S. Geological Survey (USGS) and state geological surveys are collaboratively identifying and gathering data about the spatial distribution and characteristics of critical minerals across the contiguous U.S. and Alaska. Read more about ISGS’ work locating and assessing designated Critical Minerals.

Energy storage

Carbon management

  • Geological mapping and modeling
  • Simulation of CO2 injection
  • Seismic analyses

The Carbon Storage Assurance Facility Enterprise (CarbonSAFE) is a Department of Energy-led program designed for the commercial-scale use of carbon capture and long-term geologic storage technology. CarbonSAFE builds on extensive research to reduce greenhouse gas emissions from industrial and power generation sources. ISGS leads the Midwest Geological Sequestration Consortium and conducts CarbonSAFE studies across the Illinois Basin. 

Hydrogen storage

Long-duration, low-emission energy storage at the utility scale is one of the major challenges to address during the clean energy transition. Hydrogen is a high-energy content fuel that is produced with low or zero emissions from a variety of feedstocks. Underground hydrogen storage is an option for long-duration energy storage that could be used to increase output from low-carbon power generators and balance energy supply and demand variations. The National Renewable Energy Laboratory (NREL) estimates that by 2050 over 100 million metric tons (MMT) per year of hydrogen will be required to fuel power generation, transportation, refining, and ammonia/biofuels sectors of the United States sustainable economy. This can only be met by the subsurface storage of hydrogen. The USGS, national laboratories, state surveys including ISGS, and industry partners are accelerating research, demonstration projects and screening evaluations (particularly in the Midwest, and specifically within the Illinois Basin) regarding subsurface storage.

ISGS hydrogen storage-focused projects and research

  • The study focuses on the completion of an initial screening evaluation of subsurface hydrogen reservoir performance in non-salt stratigraphy supported by the Department of Energy (DOE) Award: Phase I Concept Design – Hydrogen Storage for Flexible Fuel Power Generation: Integration of Underground Hydrogen Storage with a Gas Turbine. The outcomes: indications of optimal injection placement, caprock efficacy of shale, and minimizing co-produced brine for saline aquifers.
  • ISGS and the University of Illinois Department of Civil and Environmental Engineering are taking a leadership role in hydrogen flow-through core experiments in the Pipeline and Hazardous Materials Safety Administration (PHMSA) Award Grant: Expanding Hydrogen Storage to Porous Rock Formations – A Framework for Estimating Feasibility and Operational Considerations. Integration of actual flow-rate data into dynamic reservoir simulations will provide a more accurate representation of the reservoir performance of hydrogen in the subsurface.
  • This study focuses on the ongoing subsurface caprock and reservoir performance simulations of hydrogen in various temperature, pressure, and salinity scenarios with inputs from new research regarding capillarity, solubility, and mobility of hydrogen in the subsurface. Researchers are investigating the relevance to both saline aquifers and depleted oil and gas fields in which fill/drain cycles are daily or weekly, depending on seasonal rotation. The focus is on caprock efficacy and hydrogen losses both in the working gas and cushion gas.

Subsurface energy resources

The subsurface energy resources group conducts exploratory geologic research on the oil-bearing strata of Illinois in cooperation with the oil industry. This research has demonstrated innovative methods to extract oil and natural gas more efficiently and cost-effectively. The detailed focus on understanding and characterizing the petroleum systems of Illinois provides a strong foundation for the petroleum industry to build upon, saving significant time, effort, and resources.

ISGS houses an extensive online data archive of Illinois oil and gas well drilling records: Illinois Oil and Gas Resources mapping project (ILOIL). In addition to oil and gas records, users can view other data layers such as producing horizons, samples, core analysis data, structure contours, waterflood areas, and oil fields. 


ISGS leads efforts to leverage Illinois’ favorable geologic conditions to develop reliable, sustainable, cost-effective geothermal energy systems. PRI is a founding member of the Illinois Geothermal Coalition that works to strengthen and advance the implementation and design of geothermal energy systems in the U.S. Midwest.

This includes studying the Illinois Basin as a source of geothermal energy and a reservoir for storing thermal energy as well as investigating the feasibility of tapping Illinois’ geothermal energy resources for heating and cooling of large facilities, such as universities and military bases.


Petrography Lab

Geochemistry labs

Other resources