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Approximately 3 billion years ago, long before multicellular organisms roamed the earth, lush mounds of algae began to thrive along warm, shallow shorelines. These algal mats trapped sediment, which built up layer by layer into dome-shaped mounds. Such mounds are called stromatolites.
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Fossil formation in Wisconsin

Many people view the earth and its lifeforms as what we see today. However, both have changed dramatically through time; the evidence for this comes from something most of us see every day, but think little about: rock. Much of the rock in Wisconsin contains fossils, the remains of an
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Formula: SiO2.nH2O Amorphous Description: Opal is a mineraloid composed of spherical silica aggregates with various amounts of interstitial water. It forms under a wide range of low-temperature geological conditions. Opal may be deposited by silica secreting organisms such as diatoms
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New Publications at the Survey

Geologic map showing the Quaternary geology of Jefferson County, Wisconsin
We've recently released a number of new publications available for purchase and free to download. Titles include Wisconsin's Geologic Past (poster); Glaciation of Wisconsin; and Quaternary Geology of Sheboygan County, Wisconsin.
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2021 Year in Review

Man crouched on the ground in a wooded area next to a variety of groundwater sampling equipment.
Director’s Message The Wisconsin Geological and Natural History Survey (WGNHS) had another successful year in 2021. We began the year working remotely due to the Covid-19 pandemic, but restrictions started to ease during the spring as vaccinations became available and Covid infe
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Wisconsin Rocks and Minerals (story map)

Screenshot of title screen from story map with text reading
Ever wonder what Wisconsin’s most important rocks and minerals are? We’ve created a story map that will help satisfy that curiosity! Adapted from the WGNHS Rock Kit, this interactive story map takes viewers on a virtual tour of our state’s rocks and minerals. It̵
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WGNHS offices are open

Red wooden
In accordance with guidelines from the Division of Extension and UW–Madison, WGNHS has reopened its offices to our employees and the public as of July 6, 2021. Throughout the long closure, our staff has been working remotely, conducting fieldwork, and continuing to do research on Wisc
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2020 Year in Review

Director’s Message 2020 was one of the most unusual years in the long history of the Wisconsin Geological and Natural History Survey. January began normally, with WGNHS staff involved primarily in office projects and participating in the normal sequence of winter professional me
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Southwest Wisconsin groundwater and geology study (SWIGG)

Farmland and tree-covered rolling hills of the Driftless Area in southwest Wisconsin (photo by Eric Carson, WGNHS)
Southwest Wisconsin has fractured bedrock beneath generally thin soils, putting groundwater at risk for contamination. The purpose of this study is to improve our understanding of groundwater quality in southwest Wisconsin and to better understand how local hydrogeology and well const
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Jady Carmichael