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Introduction
The Great Lakes Geologic Mapping Coalition (GLGMC), commonly referred to as the “Coalition,” is a partnership between the U.S. Geological Survey (USGS), the U.S. States of Illinois, Indiana, Michigan, Minnesota, New York, Ohio, Pennsylvania, and Wisconsin and the Canadian province of Ontario. The member States receive funding for geologic mapping work from the USGS National Cooperative Geologic Mapping Program (NCGMP), whereas Ontario participates as a nonfunded partner. The mission of the GLGMC is to produce three-dimensional (3D) geologic maps that depict unconsolidated sediments and near-surface bedrock in the Great Lakes region of North America. Geologic maps are the basis of most earth science investigations and help support resource exploration (energy, minerals, groundwater), natural hazard mitigation, infrastructure development, and land-use planning, all of which can be used to advance economic development and strengthen national security in the Great Lakes region.
During the last few million years, the Great Lakes region has experienced repeated glacial advances and retreats, leaving behind extensive sediments, abundant natural resources, and widespread effects on the underlying bedrock geology (Swezey and others, 2022). Linked by shared histories of past glaciations, industrial agriculture, and legacy automotive, coal, steel, and manufacturing industries, the GLGMC member States collaborate to improve the understanding of the 3D distribution of the sediments overlying the region’s bedrock (fig. 1). Developing a comprehensive subsurface 3D framework of this glaciated terrain can provide earth science data to policymakers at all levels. These insights facilitate informed decisions on the exploration, use, and protection of vital resources, such as critical minerals, industrial materials, and aquifers, thereby supporting economic prosperity and the well-being of the citizens of this region.
Since its inception in 1998, the Coalition has completed more than 100 geologic mapping projects across the Great Lakes region. Each project aims to deliver geologic maps, 3D datasets, and other information that improves understanding of the geology of the Great Lakes region, with an emphasis on economic and water resources. Key deliverables include 3D geologic maps and models typically portraying sediment thickness, often derived from top-of-bedrock and borehole data. These products are developed through a combination of fieldwork, subsurface modeling, and the collection and analysis of rock and sediment cores.
To support Coalition goals, member States collaborate with scientists working on related STATEMAP, EDMAP, and FEDMAP projects. Coalition scientists also engage with Tribal Nations in the Great Lakes region to ensure that Tribal interests pertaining to Coalition work are addressed. Through this collaboration, the Coalition unites the efforts of State, Federal, and Tribal Nation stakeholders to advance geologic data production and enhance understanding of the geologic resources of the Great Lakes region.
Suggested Citation
Lopez, B., Shelton, J.L., Marketti, M., Ritzel, K., and Graham, B.L., 2026, The Great Lakes Geologic Mapping Coalition—Working collaboratively to understand the geology of the Great Lakes Region: U.S. Geological Survey Fact Sheet 2026–3010, 4 p., https://doi.org/10.3100/fs20263010.
ISSN: 2327-6932 (online)
ISSN: 2327-6916 (print)
Study Area
Table of Contents
- Introduction
- Minnesota Geological Survey Quaternary Geologic Mapping
- USGS Quaternary Geologic Mapping of the Glaciated Regions Project
- References Cited
| Publication type | Report |
|---|---|
| Publication Subtype | USGS Numbered Series |
| Title | The Great Lakes Geologic Mapping Coalition—Working collaboratively to understand the geology of the Great Lakes Region |
| Series title | Fact Sheet |
| Series number | 2026-3010 |
| DOI | 10.3133/fs20263010 |
| Publication Date | May 20, 2026 |
| Year Published | 2026 |
| Language | English |
| Publisher | U.S. Geological Survey |
| Publisher location | Reston, VA |
| Contributing office(s) | National Cooperative Geologic Mapping |
| Description | 4 p. |
| Country | Canada, United States |
| State | Illinois, Indiana, Michigan, Minnesota, New York, Ohio, Pennsylvania, Wisconsin |
| Online Only (Y/N) | N |
| Additional Online Files (Y/N) | N |