back next Ferne Clyffe Nestled in a canyon in Southern Illinois you can find the jewel, Fern Cliff. Yea I know, Illinois is flat, but here is the beauty of Southern illinois. Thw glaciers ran of out omph here and cut and dumped huge rock formations. Well, not that huge, but they are up to 90 feet in this part of the state. Enjoy this walk I took after a rain storm tha covered everything with a sheen of water.