IOWA CITY — Geologists know well that Iowa used to teem with marine life, as it once was under water.
But University of Iowa engineers and construction crews last week got a reminder when they dug up 385 million-year-old coral fossils while working on an expansion to the Seamans Center on campus.
Crews were drilling about 35 feet deep last Tuesday when they ran into rocks belonging to the Coralville Formation, which existed during the Devonian period of geologic time, according to Ryan Clark, a geologist with the Iowa Geological Survey. Iowa, at that time, sat near the equator under a warm, shallow sea, according to Clark.
“The rocks they encountered are part of what could be considered an ancient ‘reef’ similar to reefs we see in oceans today,” Clark said.
Crews working on a south annex to the Seamans Center for the Engineering Arts and Sciences building, which sits just west of the Old Capitol Town Center and south of the Pentacrest, collected several larger pieces of the coral and plenty of smaller ones, Clark said.
“They noticed it didn’t look like normal rock,” he said. “So the engineers got a hold of us and asked us to come over and look at it.”
Once on the scene, Clark confirmed the discovery of both coral and “stromatoporoids” — or spongelike animals — fossilized in the rocks.
“Sure enough, you have some coral and other things that are extinct,” Clark told them.
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The discovery is not necessarily unique — as experts have determined these fossil beds underlie Iowa City and can even be seen in the small cliffs along the Iowa River and Riverside Drive. But Clark said this week’s find is more evidence this area once was under an ocean.
“Iowa has actually spent a lot of its geologic path under water,” he said.
The UI Paleontology Repository, which contains more than 1 million fossils in trust for the state of Iowa, plans to add some samples from the campus find to its permanent collection.
“I selected a few fossils for a representative sample,” said Tiffany Adrain, a UI collections management specialist. “I really like the story — that they come from under the new Seamans Center.”
Construction of the $37 million, 65,000-square-foot center addition began in December and is expected to wrap up in October 2017. It is adjoining the current Seamans Center and extending the complex south, toward Burlington Street, answering a “significant need for state-of-the-art facilities as engineering experiences significant growth.”
Several of the project’s construction workers and engineers have asked to keep some of the artifacts “as souvenirs of their discovery,” which Clark said UI officials plan to “cut and polish” for them.
This isn’t the first time construction collided with history on campus. In winter 2014, crews working on flood-related reconstruction near the Iowa Memorial Union unexpectedly exposed historic artifacts in Hubbard Park. Emergency excavations that winter revealed historic deposits — probably dating to the Great Flood of 1851.
Those initial finds prompted archaeologists to return to explore other parts of the park, turning up artifacts like house foundations, refuse-filled pits and a root cellar — all of which predated the Civil War.