This collection shows the changing nature of Wisconsin’s bedrock geologic maps, from 1869 to today. Click on the images to view a low-resolution version of the entire map or on the links in the descriptions to download full-size PDFs.
Adapted from a presentation by Bruce Brown, former WGNHS geologist.
1869 | Lapham
First real state geologic map of Wisconsin.
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1879 | Irving
This map focuses on the geology of Wisconsin’s mineral resources. Citation
1881 | Chamberlin
First systematic large-scale geologic mapping survey of Wisconsin.
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1898 | Buckley
This map was prepared for a bulletin on building and ornamental stone. Note the absence of detail in the Precambrian. View PDF
1900 | Buckley
Map for bulletin on clays and shales for the brick and tile industry. The geology was simplified to address a specific issue. View PDF
1911 | Hotchkiss and Thwaites
This large map shows geology and roads. It provides detailed descriptions of each formation. View PDF
1915 | Weidman
Map accompanying bulletin about artesian conditions. Geology is generalized. Shows contours of the top of the Precambrian.
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1928 | Bean
This map is very similar to Weidman’s 1915 map. Note the minor changes in the edge of the Precambrian.
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1939 | Bean
Perhaps the most significant change to this map was the expansion of the Devonian in eastern Wisconsin. This version remained virtually unchanged until 1982.
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1982 | Mudrey, Brown, and Greenberg
The current state bedrock map was produced in response to growing interest in the Precambrian following discovery of massive sulfide deposits in the 1970s. This map is the first to emphasize detail in the Precambrian.
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