March 24th, 2025
Mel Reusche, WGNHS Communications and outreach specialist
Ridges and valleys, lakes and marshlands, rolling hills and lakeshore cliffs – the landscapes we recognize across Wisconsin are the result of fascinating and complex geologic processes. A new, statewide map published by UW-Madison Extension’s Wisconsin Geological and Natural History Survey tells the story of how the landscape was shaped over the last 2.58 million years. Quaternary Geology of Wisconsin describes the blanket of sediment that covers Wisconsin’s solid bedrock and how it got there. These deposits reveal evidence of ice sheets, wind, water, and erosion and hint at the deep geologic history of Wisconsin and the lasting effect it has on our daily lives.
The long-awaited map is fifty years in the making. It updates and improves a map originally published in 1976. Since then, dozens of Wisconsin Geological and Natural History Survey geologists and UW-Madison Extension partners have worked to integrate modern data from laser-based elevation surveys, new county-scale geologic maps, and well drilling records into the new version. As a result, this new publication contains a comprehensive and more accurate set of sedimentary units and landforms across the state.
Many of these landforms will be recognizable to Wisconsin outdoor enthusiasts, such as those exploring the Ice Age National Scenic Trail. The trail winds its way along the edge of the glacial deposits in the state from St. Croix Falls in the north, to Janesville, and then loops back up to Sturgeon Bay. Melissa Pierick at the Ice Age Trail Alliance says “This map wonderfully illustrates a topic that can sometimes be confusing to non-geologists! It illustrates what our publications have only ever described in words. In a glance, hikers will be able to see the different terrain they’ll encounter and the sediment types they’ll walk on.”
Along with classifying landforms, the map identifies loose materials like gravel, sand, and clay that range in thickness from 0 to 600 ft across the state and play a variety of important roles. For example, these sediments hold millions of gallons of groundwater used for drinking water and agriculture, contain sand and gravel used for construction, and support fertile soils. The updated map not only tells the fascinating history of our landscape for outdoor enthusiasts, but also provides critical information to county officials, private construction companies, and science educators among others.
For J. Elmo Rawling, WGNHS Quaternary geologist and project lead, this map is about more than providing updated sedimentary units and landforms. “Hopefully this map will be hanging on classroom, visitor center, library, and agency walls across the state for decades and inspire an interest in the history of how glaciers, rivers, wind and other surface processes shaped Wisconsin’s landscapes.”
Visit the project webpage to learn more and download the map for free today.
More information
For more details, contact one of the following WGNHS Quaternary geologists:
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J. Elmo Rawling, III, elmo.rawling@wisc.edu, (608) 263-6839
- Eric Carson, eric.carson@wisc.edu, (608) 890-1998