The Chicago Department of Aviation is holding a contest to name a boulder found under O’Hare International Airport during construction work.
The 50-ton boulder was found about 30 feet below the surface of the airfield at O’Hare during excavation of the South Detention Basin, a stormwater management facility. The work is part of the ORDNext project — the largest terminal expansion in the history of the airport.
The boulder is about 11.5 feet wide, 8 feet deep, and 7.5 feet tall. A geologist working for the ORDNext project said it was made of dolostone, a sedimentary carbonate rock made up mostly of the mineral dolomite, or calcium magnesium carbonate — chemical formula CaMg(CO₃)₂.







