Active coalition project areas are shaded green. The purple line represents the extent of continental glaciation.

The state geological surveys of Illinois, Indiana, Michigan and Ohio joined with the U.S. Geological Survey (USGS) in 1999 to form the Great Lakes Geologic Mapping Coalition—a union of state and federal scientists engaged in geologic mapping of the Great Lakes states. The Coalition is expanding in 2008 to include four more states bordering the Great Lakes with similar geological issues—Minnesota, New York, Pennsylvania, and Wisconsin.

This web site of reduced-scale products is a sampling of Coalition- and state-funded mapping that has taken place in four focus areas since the beginning of the program in 1999.

The purpose of this web site is to show examples of products and to emphasize the type of information needed for ground-water assessments, environmental protection, mineral resource availability, and earth hazard mitigation. For more information see the 2008 Information Sheet.

Need for three-dimensional geological information

Decision makers, planners, educators, engineers, and consultants evaluate complex and competing public policy options involving earth resources. Therefore federal, state, and local governments and private industry need uniform and unbiased information about earth materials for managing water, land, and biological resources to ensure economic growth, to meet the natural resource needs of an increasing population, to assess hazards, and to manage the environment in a sustainable manner.

Three-dimensional geologic information is required for informed decisions regarding many issues, such as:

• Quality, quantity, distribution, and accessibility of surface and ground water
• Environmental management and mitigation of land and water contamination
• Acceleration of the permitting processes of regulatory agencies
• Industrial, commercial, residential, and infrastructure siting and construction
• Agricultural land loss, erosion, sedimentation, and agrichemical use
• Coastal erosion, landslides, radon, floods, and earthquakes
• Habitat alteration and biodiversity
• Aggregate sources for construction

Coalition products enable the user

The overriding intent of the Great Lakes Geologic Mapping Coalition is to enable the user by combining and utilizing the expertise and resources from five geologic surveys to answer key scientific questions, such as the origin, nature, distribution, and resource potential of the glacial deposits that cover our states. It will provide:

• Information critical for energy and mineral resource management
• Updatable, three-dimensional geologic maps that delineate earth deposits from land surface to bedrock
• Maps that support critical decisions concerning environmental management, natural resources, and hazards
• Dynamic databases that enable users to ask specific questions and obtain answers about earth resources

Unique geology—a remnant of the Ice Age

Over the past million years, continental ice sheets repeatedly advanced and retreated over the central Great Lakes region, leaving thick deposits of mud, clay, sand, and gravel. The three-dimensional (3-D) knowledge of the characteristics, distribution, and thickness of these deposits is required to address issues important to decision makers.

Our similar geologic heritage combined with the need to resolve common societal issues provides a shared set of circumstances for the four state geological surveys and the USGS to address jointly.