NewsMilwaukee Tonight


Milwaukee Formation: The fossil you can only find in Milwaukee

Posted at 6:55 PM, Apr 04, 2022
and last updated 2022-04-05 13:17:11-04

MILWAUKEE — When you think of Milwaukee, most people probably think about breweries, curds, and sports. But one thing is being overlooked that predates even Milwaukeeans love for brats by hundreds of millions of years. It's the Milwaukee Formation.

The Milwaukee Formation is a category of rocks and fossils that can only be found in Milwaukee County and a bit of Ozaukee County. These fossils date back 390 million years to the Devonian Period, which is before even the dinosaurs. In fact, these fossils are of all marine plants and animals. That long ago, Wisconsin was covered by a shallow ocean.

"The types of fossils in the ecosystem that was here is different from the entire region in the Midwest where the same rocks are found," Scott Schaefer, the collections manager at the Weis Earth Science Museum in Menasha, said. "You can hand me 10 fossils from our package of rocks and I will be able to exclusively (know it is a) Milwaukee Formation, not the Devonian of New York, Michigan, or elsewhere."

Meaning, these are incredibly distinct to a very small region of the world. It just so happens that the small region is the Cream City. What's more, what sets these fossil apart is the incredibly high biodiversity found within each rock.

The Thomas A. a Greene Geological Gallery at UW-Milwaukee has an entire collection of Milwaukee Formation. They even have a uniquely Milwaukee named fossil too. It's called the Orthospirifer Milwaukeensis.

“It's a shell creature found only in our rocks here. So if you were to hand me a fossil that has that organism in it, I would be able to tell that its from Milwaukee," Schaefer said.

While the gallery has the best collection of Milwaukee Formation, you can actually find it along the shores of Lake Michigan on your own. Go to Bradford Beach or Sheridan/Atwater/Doctors/Grant Parks to search for them yourself. Look for dark rocks with light lines.

Report a typo or error // Submit a news tip

milwaukee tonight


Nominate your 'Hidden Gem' for Milwaukee Tonight

Milwaukee Tonight focuses on the people, places, and events that make the community special. From artists to architecture, food to festivals, neighborhoods to nightlife - this show is a nightly reminder that our city is filled with stories to be proud of. Watch weekdays at 6:30 p.m. on TMJ4.