Prairie Research Institute

Illinois State Geological Survey

Illinois Geologic Mapping Advisory Committee

About the Committee

The IGMAC meets annually in a forum to discuss geologic mapping needs and seek regional mapping coordination and opportunities. Its primary function is to review and approve long-term plans by ISGS for geologic mapping, as mandated by the USGS National Cooperative Geologic Mapping Program. This review is necessary for ISGS to participate in the STATEMAP program, in which the objective is to establish the geologic framework of areas vital to the welfare of the United States. Also reviewed are mapping plans within the Great Lakes Geological Mapping Coalition, and other mapping initiatives in the state.

The NCGMP renewed its vision and mission in 2021:
Brock, J., Berry, K., Faulds, J., Berg, R., House, K., Marketti, M., McPhee, D., Schmidt, K., Schmitt, J., Soller, D., Spears, D., Thompson, R., Thorleifson, H., and Walsh, G., 2021, Renewing the National Cooperative Geologic Mapping Program as the Nation’s authoritative source for modern geologic knowledge: U.S. Geological Survey Open-File Report 2021–1013, 10 p.,

Isn’t Illinois Already Mapped? Although geologic mapping has been ongoing in the state since the inception of ISGS in 1851 and before, much of the state has been mapped only at small scales (large areas and low detail). The STATEMAP program emphasizes 1:24,000 scale (1”=2000’) mapping. This scale is suitable for many analyses and is a vital guide for higher-resolution mapping for particular projects. The US Geologic Framework Initiative supports compiling the large-scale maps into regional and ultimately national maps:

Annual Meetings

The next IGMAC meeting will be on 5 October 2023.

2022 Presentations


Committee Members

The IGMAC includes representatives from the Prairie Research Insitute (Natural History, Archaeology, and Water Surveys), the Illinois Department of Natural Resources, the Illinois Department of Public Health, the Illinois Emergency Management Agency, the Illinois Department of Transportation, groundwater professionals, the coal, oil, gas, and aggregate industries, academia, engineers, and city and county planners. The Illinois State Geologist, Dick Berg, is an ex-officio member and serves as Secretary. Alison Anders (University of Illinois Urbana-Champaign) is the Chair for 2022-2024, and Joanna Colletti (McHenry County, Dept. Planning and Development) is Vice-Chair. The committee abides by a set of Bylaws and their activities are summarized in this IGMAC Fact Sheet. For further information, contact Drew Phillips (ISGS), IGMAC Coordinator.