New map spotlights geology of Starved Rock State Park

This map was created to provide visitors to Starved Rock State Park with a deeper understanding of the geology that contributes to the natural beauty of the park. Exposed rocks that protrude from the bluffs within the park and along the Illinois River reveal sediments that once accumulated millions of years ago on the floor of a shallow sea, along ocean beaches, and on deltas built by massive rivers discharging into the ocean. Then, only thousands of years ago during the most recent ice age, the canyons formed as glacial meltwaters flowed through the river valley and began to erode the landscape. At times, violent torrents of meltwater from nearby melting glaciers sent water rushing through the Illinois River valley, widening and deepening the canyons. This action of water on rock over thousands of years created the unique bluffs, canyons, waterfalls, and river valleys for which the park is famous, and these same geologic processes continue to shape the landscape today.

Special Report 8, Geology of Starved Rock State Park and Surrounding Area, La Salle County, Illinois, by Jason F. Thomason, is now available free for download. Print copies are available for order online.