Impact of Large Rock Fall in Starved Rock State Park
The park superintendent of Starved Rock State Park and an Illinois Department of Natural Resources district manager requested the investigation of a large rock fall that occurred below the Owl Canyon observation platform. Illinois State Geological Survey engineering geologist Robert Bauer met both representatives at the park on October 16, 2009, and investigated the fall of the cliff face into the Illinois River. The fall is located on the cliff below the platform that left an overhang near the platform's base. River erosion undercut the base of the cliff back to joints that parallel the cliff face, which caused the fall. The investigation found other slow rock movements at the top of the cliff that tilted two of the platform's six supports. Several pages of composite annotated pictures were presented to the park superintendent and district manager showing the fall's projection to the top of the cliff in relation to the platform's position and other precarious undercut rock masses near the platform. The platform area has been closed until the platform can be moved back from the current edge.