116 3rd St SE
Cedar Rapids, Iowa 52401
A Day Away: Coralville Lake’s Devonian Fossil Gorge a trip back in time
The gorge, one of only two sites like it in the country, offers visitors a chance to learn about life on earth millions of years ago
IOWA CITY — Some 375 million years ago, Iowa was under water. The temperatures were hot, and brightly colored corals and huge fish moved through the shallow sea.
Visitors can see a glimpse of this prehistoric world at the Devonian Fossil Gorge at Coralville Lake, 2850 Prairie du Chien Rd. NE, Iowa City, a 15-minute drive south from Cedar Rapids.
One of only two sites like it in the country, the Devonian Fossil Gorge was uncovered in 1993, when floodwaters ripped out a campground that sat on top of what is now the gorge. When the waters receded, they revealed thousands of fossils preserved inside the limestone.
The area flooded again in 2008, stripping back more sediment and revealing more fossils.
“It doesn’t mean we’re the only place where it happened, but this is one of the only two places that’s been uncovered to our knowledge,” said natural resource specialist Shawna Polen. “It’s pretty unique in the whole U.S., that this is one of two locations.”
More than 1.4 million visitors explore the gorge each year, from around the United States and the world.
For those who have visited this popular spot before, new additions coming to the gorge will be worth a repeat trip.
The new Junior Ranger app is launching soon, giving kids and adults a chance to get a guided tour of the gorge from their phone.
Kids who unlock all of the stops in the fossil gorge on the app can get a Junior Ranger badge from an Army Corps of Engineers ranger at the park.
Polen designed the Junior Ranger program to encourage more interaction with park rangers, who children often only see enforcing rules in the park.
The program will launch at 10 Army Corps of Engineers sites this year, and Coralville will be the first site to have the app.
“It gets that in-person face-to-face contact with a ranger,” Polen said. “That lasting memory is what I’m asking for — hoping to spark the light bulb in a child or family.”
The Coralville Lake Visitors Center also is getting an update, eventually having an exhibit demonstrating the history of the lake, from the Devonian period to the time the Army Corps of Engineers took control of the property in the 1940s. The center is open during the remodeling, but doesn’t offer much to see right now.
The signage that helps welcome visitors and orient them to the different kinds of creatures that can be seen in the gorge is also getting an update.
Another update coming soon is a life-size recreation of “Dunkley,” the lake’s mascot. He’s a Dunkleosteus — a giant armored fish that swam the sea during the Devonian period, around 350 million years ago.
The 33-foot by 8-foot replica will eventually have a home in the gorge.
Stepping back through time
The gorge is 19 feet down from the visitors pavilion that marks the entrance.
As curious visitors make their way down the ramp to the gorge, they’ll see rocks which get progressively older, representing the law of superposition.
The main kinds of fossils can be determined by their different shapes. Hexagonaria coral is shaped like hexagons. Crinoids can be spotted from their small round shape.
“We tell kiddos to look for the Cheerios,” Polen said.
Horned corals look like bones, and brachiopods look like sea shells.
Thousands, possibly millions of fossils, are pressed into the limestone, and can be seen on almost every surface.
Visitors are asked to leave things as the found them — taking fossils from the gorge is not permitted. Sturdy shoes also are a must, since the rocks underfoot are uneven.
Old life supports new
The fossils aren’t the only attraction in the gorge — small pools of water are home to insects, animals and plants.
Polen said although the rock in the gorge is dead, it supports all kinds of life.
When Polen takes kids on tours of the gorge, she tells them to be quiet and listen carefully for the sounds of nature that can be heard — frogs ribbiting, birds in the distance, and the buzz of insects.
“We tend to be too loud on hikes or tours — we miss out on the true beauty of nature,” she said.
The uneven surface often fills with small pools of rainwater, where frogs and dragonflies make there homes, and tadpoles can be spotted swimming in the water — although visitors can’t take any tadpoles with them unless they have a fishing license.
Polen said it’s not unusual to see snakes in the gorge as well, hiding in cracks from the heat of the sun.
A day at the lake
While the Fossil Gorge is Coralville Lake’s most unusual attraction, visitors have plenty of other recreational opportunities to explore after taking in the sights.
Camping: More than 500 campsites are spread out among three campgrounds at the lake. Reservations are highly recommended.
Swimming: The lake has two designating swimming beaches for cooling off after visiting the fossils.
Other popular uses: Picnic areas with shelters; fishing; boating ($5 launching fee); two disc golf courses; sand volleyball; hiking and mountain bike trails.
Information: recreation.gov/camping/gateways/158 or mvr.usace.army.mil/Missions/Recreation/Coralville-Lake/
Comments: (319) 368-8827; firstname.lastname@example.org