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Unearthing the Past: A Guide to Fossil Hunting in Wisconsin

Updated: Mar 3

As much as I loved dinosaurs growing up, I was about a thousand miles away from the nearest location where dinosaurs fossils could be found. Today, I have accepted that fact, but it doesn't mean I can't go out and find fossils here in the Badger State. It's just that the fossils are a little bit different from dinosaurs. I want to share as much as I can with you so you and your family can successfully find fossils.

A stone from Fennimore, Wisconsin loaded with small invertebrate fossils
A stone with hundreds of small fossils from Fennimore, Wisconsin

I am an avid fossil collector. With my full-time job, I travel all over the state of Wisconsin so, when there isn't snow on the ground and I drive past a nice-looking outcrop of rocks, there's a pretty good chance I'll turn around and take a peek because I never know what I might find. As a kid, my dad did the same thing with me near Fennimore and in about thirty minutes, we filled two five-gallon buckets full of fossilized seashells. It was one of the most enjoyable and memorable moments of my youth, one I will never forget (hopefully). A few years ago, I returned to that spot and, unfortunately, it had grown over with grass, weeds, and shrubs. The rocks were no longer exposed.


Bedrock Layers

The rock layers in Wisconsin are interesting. Since we had those darn Ice Ages come again and again over the past few million years, the glaciers scraped away almost all of the fossil bearing rocks from the northern two-thirds of the state, which stinks for me because I currently live in this area.

Here's a list of some places I have found or were shared with me:

Locations of Fossils in Wisconsin (Expand List)


The best places to find fossils in Wisconsin are typically in the lower third, and along Lake Michigan. Take a look at the map on the right, and you'll see what I mean. Again, we can blame the glaciers for the lack of fossil-bearing rocks. If you click on the map, it will bring you to the Wisconsin Geological and Natural History Survey's website where they have more fossil locations (though I checked those links and got back a bunch of 404 errors... looks like they haven't maintained the site in a while). Though this map is nice, when you are out driving around looking for suitable rock outcroppings, you'll need something a bit more detailed because a bedrock layer can change 100 feet down the road, or from one hill to the next which will be the difference between finding nothing and loading two five-gallon buckets full of seashells and coral. For that, I recommend an app called Rock'd, which was designed by the good people at UW-Madison. It is absolutely full of amazing resources and consists of a world map that shows the topmost layer of bedrock. It is GPS integrated, so it can follow you. If you click on your location in the map area, it will give detailed information about the bedrock below you including age, what it's made of, as well as any pertinent resources they feel should be listed (in case you're the type who loves looking that stuff up and reading long peer-reviewed articles).


Common Fossils in Wisconsin

Here's a video I created back in the days when I ran a non-profit called Colossal Fossils. It highlights some of the fossils that are commonly found in our state, which include:

  1. Brachiopods: These are marine animals with two shells, resembling clams. Brachiopod fossils are often found in sedimentary rocks from the Paleozoic era.

  2. Trilobites: Extinct marine arthropods, trilobites left behind distinctive segmented exoskeletons. They are common in rocks from the Paleozoic era and happen to be the Wisconsin state fossil.

  3. Coral: Fossilized remains of ancient coral can be found in some rocks in Wisconsin, particularly in those formed during the Silurian and Devonian periods.

  4. Gastropods and Bivalves: Fossilized snails (gastropods) and clams (bivalves) are often found in marine sedimentary rocks.


A climactichnites trace fossils from Mosinee, Wisconsin
A climactichnites trace fossil from Mosinee, Wisconsin

Some of the neatest fossils I have seen are from an area near Mosinee, Wisconsin. For some reason, the glaciers left a small patch of sandstone undisturbed (everything around it is volcanic rock), and here you can find the oldest and best preserved jellyfish fossils in the world. Growing up to three feet wide, they all date to approximately 500 million years ago and they are gorgeous. In addition to the jellyfish, you can also find strange trackways known as climactichnites, which were made by a mystery animal that no one has found yet (or so we think).


So there you go. Grab a bucket, and hit the road. Don't forget to get permission to walk on property before you leave the roadside. Best of luck, and let us know if you find anything. Happy hunting!


Resources

Fossil Spot - WI (more sites where you might find fossils)


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