Illinois State Geological Survey Field Trip and Guide to Geology of Starved Rock and Matthiessen State Parks

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What does a geologist do?

That’s the question that Mike Chrzastowski used to begin his first talk of the day on a field trip conducted by the Illinois State Geological Survey at Starved Rock and nearby Matthiessen State Parks this past October. Chrzastowski was one of a team of geologists leading the trip, which was designed to acquaint participants with the geology, landscape, mineral resources, and biodiversity of the area surrounding these two scenic and popular state parks.

In answer to the question of what geologists do, I and other field trip participants generally agreed they looked at rocks. Chrzastowski allowed for that, but he emphasized another aspect of their work. “Geologists,” he said, “tell stories.”

And stories were the order of the day. As we stood atop Starved Rock itself, a hundred twenty-five feet above the Illinois River, Chrzastowski told how torrents of meltwater from lakes formed by retreating glaciers—flows more powerful than today’s Mississippi River—had cut down through the surrounding plains to create the Illinois River Valley as we know it.

At another stop, we stood beneath Council Overhang, a fifty-foot high natural amphitheater in the side wall of Ottawa canyon with such perfect natural acoustics that our guides didn’t have to raise their voices to be heard. There we learned how the layers of sandstone and dolomite visible in the cliffs of the park formed hundreds of millions of years ago, as ancient seas repeatedly flooded the area and then receded.

We also learned how the three-sided box canyons opening out to the river valley had come to be, formed by small streams from the surrounding uplands cutting farther and farther back into the cliff face over time.

Now, don’t get me wrong, the cliffs and other rock formations at Starved Rock are spectacular enough to look at without knowing anything more about them. But for me, the pleasure of learning how they came to be made the experience all the richer.

The Illinois State Geological Survey will host two more field trips on the geology of Starved Rock and Matthiessen State Parks in spring of 2006. There is a twenty-five dollar fee for the trips, which are capped at a hundred participants, and advance registration is required. More information about State Geological Survey field trips and how to sign up for them is available at the Survey’s website

If you’ve got plans to visit the parks I’ve been talking about before spring, or field trips just don’t grab you, you might be glad to know that the Survey has also recently published a book about them. It’s called Time Talks: The Geology of Starved Rock and Matthiessen State Parks, and it’s available at the Starved Rock Visitors Center and through the Survey’s public information office in Champaign.

Time Talks is a concise, clearly written, beautifully designed guide intended to help park visitors read the landscape for themselves, and it tells many fascinating stories.

Of course, that’s one thing geologists do.

Illinois State Geological Survey
http://www.isgs.uiuc.edu/