Apple River Canyon State Park Illinois River Confluence

This dramatic 200-foot-deep canyon cuts through Ordovician limestone and dolomite, creating Illinois’ deepest gorge north of Starved Rock. The canyon walls expose fossil-rich rock layers dating back 450 million years, with spring seeps creating year-round waterfalls. Stone foundations from the old Millville mill operation still dot the canyon floor, and the cool microclimate supports rare ferns and mosses typically found much farther north.

Access the canyon floor via steep limestone steps from the park road. The trail can be slippery when wet, and flash flooding is possible during heavy rains. Best visited in spring for wildflowers or fall for colors, though the gorge stays cool even in summer heat.

Illinois' deepest canyon with fossil-rich walls