Trail heads along 430-million-year-old cliff

Peninsula State Park's Eagle Trail winds along the Niagara Escarpment and makes
for some spectacular view. Photo courtesy Wisconsin DNR.

Day hikers can explore ancient 150-foot cliffs that offer fantastic views of Lake Michigan at Wisconsin’s Peninsula State Park.

The 2-mile looping Eagle Trail sits on the beautiful Door Peninsula at the edge of the state’s second most visited state park. A popular trail, it will be busy during the park’s peak season.

Map of Eagle Trail, courtesy Wisconsin DNR.

To reach the trailhead, from Sturgeon Bay take Wis. Hwys. 42 and 57 north onto Door Peninsula. When the roads split, take Hwy. 42 to the peninsula’s northeast side. Once past County Road A (northeast of Fish Creek), turn left/north onto Shore Drive for the park entrance. The road passes through a golf course and then a beech forest. After the entrance station, park in the Eagle Panorama lot.

The trail begins a steep descent from the lot atop Eagle Bluff down to the cliff’s base. When you reach the bottom, go right/east.

Niagara Escarpment
Stretching beyond the rocky shoreline is Green Bay, a narrow triangle of water that on a map looks like the empty space between a thumb and the main part of a mitten. The bay is part of Lake Michigan.

Equally impressive is the limestone cliff to the trail’s right/south. Part of the Niagara Escarpment, the massive bedrock formation forms the Door Peninsula as well as cliffs in Michigan’s Upper Peninsula and even Niagara Falls hundreds of miles to the east.

The bluffs began to form about 430 million years ago as sediment from the surrounding land settled as mud, trapped beneath algal mats, on the tidal flats of a saltwater sea. Over the eons, this sediment tuned into limestone piled more than 150 feet high. The cliffs along the trail are so high that as afternoon arrives, they cast a shadow over the forest and waters below.

We can see the erosion-resistant cliff thanks to the power of glaciers during the last ice age, which dug out softer sediment in the basin that now forms Lake Michigan. Wave action from a much higher lake, swollen with glacial meltwater, cut caves into the cliff wall.

As walking, watch for springs that come out of the cliff walls. The water finds fractures leading to the cliff’s side are easier to flow through than the hard limestone below it.

These springs help nourish a vertical forest of northern white cedar trees. Common in eastern Canada, these fragrant trees can grow up to 50 feet tall and two feet around.

Eagle Tower
The shady cliffs harbor a number of microhabitats alive with rare crustaceans and snails. Some of the snail species are rare. Because of this, you’ll want to stay on the trail, even though at times it is narrow, rocky, or laced with tree roots.

In addition to the white cedars, ferns, thimbleberry, and several flowers, especially trilliums, can be found trailside. You’ll also spot cranberry viburnum.

As the trail near Eagle Harbor, it begins a steep ascent back to the clifftop. Once there, it runs north a little off of Shore Road then turns west as it crosses the park road just in front of the entrance station.

Next it runs through the beech forest, crossing the Sentinel Tail along the way. Taking the Sentinel Trail right/north heads to Eagle Tower, a 75-foot observation post atop Eagle Bluff. As of 2015, the tower was closed to the public.

Continuing straight on the Eagle Trail heads to Shore Road. Cross it, and you’re back at your parking lot.

Learn about trail guidebooks available in the Hittin’ the Trail series.