Perhaps The State’s Best Hidden Treasure, Hardly Anyone Knows This Incredible Coral Reef Exists In Wisconsin

If you live in Wisconsin, a bit of the ocean might be closer than you think. Millions of years ago, a giant sea covered much of what's now North America, and in some places, coral reefs formed. In Grafton, a city park is now built on top of one of these ancient fossil reefs. Lime Kiln Park is a historic Wisconsin place that’s also home to some impressive ruins, as well as bits of the old reef. The park is well worth a visit – here’s what you need to know.

Lime Kiln Park is a Grafton community park. It’s located between Highway 57 and the Milwaukee River, between Grafton and Cedarburg.

The park is home to impressive historic lime kilns. Back in the 1800s, they were used to produce lime for building and agricultural uses.

There was a quarry in what’s now the park. While much of the activity was centered on extracting lime for the kilns, some stone was also mined. It can be found in old buildings like the Immaculate Conception Catholic Church in Saukville. If you look closely, you can see coral in the stonework.

This ancient reef was formed about 400 million years ago, long before the age of dinosaurs. The reef was about five meters thick and 60 meters wide. While a lot of mining took place here, plenty of exposed stone remains in various areas.

While the park is built on some interesting geologic history, most people who visit probably aren’t thinking about ancient seas. The park has a frisbee golf course, volleyball courts, a canoe ramp, and an archery range.

But if you look around, you may see some old coral and ancient fossils – it’s a chance to get a glimpse at what the world was like here, a very long time ago.

Learn more about Lime Kiln Park on the Village of Grafton website. When I was a boy, I was amazed by some of the fossils I discovered on Wisconsin beaches - I would have loved this place! If you need some gear for your next fossil hunt, REI has you covered. And here’s where to find more of the state’s best attractions.