During the summertime, Estabrook Park is a prime location to enjoy beer gardens, bike the Oak Leaf Trail and experience the outdoors. But Bubbler Talk listener, Sophia Heyn was interested in not just the outdoor activities, but the history of the ground underneath Estabrook Park.
Heyn is a student at the UW-Milwaukee School of Freshwater Sciences. She took a course to learn how to use the mapping program ArcGIS and was assigned to investigate a waterway and how it has changed over time. She chose the southern Milwaukee River in the Estabrook Park area. What she found, prompted her to submit a question to Bubbler Talk.
“While I was sort of looking into things that could have caused the changes in the river there, I ran into like one sentence of mining happening around the area that is today Estabrook Park. I was sort of curious. I just couldn't find more,’’ Heyn says.
To learn more about this chapter in the Milwaukee River’s history, Heyn and I met up with Cheryl Nenn of Milwaukee Riverkeeper at Estabrook Park.
The history of quarrying in this area begins with what’s called the Milwaukee Formation, a mass of rock and fossils unique to Milwaukee County.
Although very similar, quarrying is the extraction of materials from the earth's surface, while mining refers to extractions below the surface.
The Milwaukee Cement Company began quarrying limestone from the Milwaukee River to use for cement in 1875. That continued until 1911 when the cheaper alternative of “Portland Cement” put the company out of business.
Cheryl Nenn points out evidence of that history along the river. We’re looking at Estabrook Falls, which can be seen from the park’s beer garden.
“So, normally you can see like a waterfall here and so this is like a ledge that’s kind of a remnant from the mining because it was just a very hard ledge. So they mined this whole section of the river, all the way even up stream of Hampton, which is the road you see up there. Basically, from bank to bank the whole river was mined for limestone, gravel, sand, aggregate — all that came out,” Nenn says.
While limestone was the main prize being extracted from the Milwaukee riverbank, some took interest in other minerals that make this area a geological wonder.
The rare mineral millerite was discovered in the park. Millerite has a high percentage of nickel that is highly sought after by collectors.
Samples of the mineral can be found at the UWM Thomas A. Greene Geological Museum.
Nenn points to one large quarry, filled with water, that is still visible in Estabrook Park—the Blue Hole. It used to be a popular but dangerous swimming spot for locals after the quarry closed. Nenn says there is also another large quarry that was used as a landfill by the city until it was turned into the current UWM Park and Ride lot.
We followed her to visit the Blue Hole.
“This is the Blue Hole. This was the whole area that was essentially mined back in the day for the Milwaukee Cement Co. from 1875 to 1911 ... and it’s very deep. This is a remnant of the mining operations, and the parking lot is a remnant, and that parking lot quarry was just solely filled with trash and is a current-day parking lot. But this is still here, and it’s kind of an interesting ... resource,” Nenn says.
The quarry is on the east side of the Milwaukee River, surrounded by recreational trails. The man-made lagoon blends in almost seamlessly with the park, aside from pieces of concrete that reveal the area's industrial past.
“I live relatively close to the Lannon quarry, so it’s interesting because, to me, it seems a little bit small,” Heyn says.
While the quarries remain a unique treasure in the park, the extraction of limestone and other minerals from the landscape has led to ongoing struggles with downstream flooding and sinkholes.
“It’s really interesting to know all the different things and see how there are all these connections to other things, too,” Heyn says.
Heyn is glad she got to explore the geological past she accidentally discovered during her introduction to ArcGIS.
When: April 10, 2025
Time: 7:00 p.m.
Where: Gathering Place Brewing Company (Riverwest)
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