O'Hare Construction Crew Unearthed 50-Ton Boulder
A 400-million-year-old rock discovered during airport expansion is now the subject of a public naming contest.
Updated on Sept. 21, 2026 in Geology
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In June 2026, construction crews unearthed a 50-ton dolostone boulder while excavating a stormwater detention basin at O'Hare International Airport. The rock, which reached its current form between 12,000 and 15,000 years ago, is now on public display at the airport's Multi-Modal Facility.
Why it matters
The discovery occurred during the massive $8.8 billion terminal modernization project, highlighting the deep geological history underlying Chicago's critical transit infrastructure. The city has since turned the find into an engagement opportunity, accepting over 2,300 public naming submissions.
The boulder, identified by a professional geologist as dolostone—a sedimentary rock composed primarily of calcium magnesium carbonate—weighs 50 tons and was found 30 feet underground. Its geological material is approximately 400 million years old.
The players
Chicago Department of Aviation
The municipal authority managing O'Hare International Airport and overseeing the $8.8 billion terminal modernization project.
Ron Pitelka
An excavator operator who helped unearth the 50-ton boulder during the terminal expansion.
Matt Tracy
A bulldozer operator who worked alongside the excavation team to clear the detention basin.
The details
Excavator operator Ron Pitelka and bulldozer operator Matt Tracy discovered the boulder using a Caterpillar 352 excavator while moving soil between basins. The geological age of the rock refers to its formation as sedimentary deposit during the Silurian period, while its physical shape was refined by glacial activity 12,000 to 15,000 years ago.
Timeline
June 2026: Construction crew unearthed the 50-ton boulder.
September 2026: The city continues to accept naming contest submissions.
The Tech Race
This find follows a pattern of unexpected geological discovery within the O'Hare Terminal Area Plan. It marks a departure from standard infrastructure debris, forcing the city to integrate the 400-million-year-old rock into the airport's public design landscape.
Travelers passing through O'Hare can view the rock at the Multi-Modal Facility, where it currently resides on public display. Residents can participate in the naming process, with finalists to be selected by the city before the final public vote occurs.
The takeaway
The boulder underscores the significant geological features hidden beneath active urban construction sites. Keep an eye on the official Chicago Department of Aviation announcements for the final voting link to name the rock.
What happens next
The city will finalize the list of names for the boulder shortly, with the public voting period expected to conclude in approximately one week.
Further reading
Learn more about local site history and terrestrial findings in Geology.
Source note: This article includes information reported by Chicago Tribune.
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