Waterfalls and climbing rock walls.
The Big Rocky Hollow Trail isn't the only trail that starts at the parking area. Cross the stepping stones over the creek to find a place where the trail forks in three. Look for the sign for the Rebman Trail at the right-most fork. This short walk leads to a small canyon punctuated by a pair of picturesque waterfalls (best water flow is in the spring or after a large rain event).
Also on this trail is a 75 foot cliff face that has been designated for climbing and repelling. It is great for novice repelling and climbing for more advanced climbers.
This portion of the park was donated in 1929 by Emma Rebman, and some historical markers remain to show her impact to the state park.
George Rogers Clark and his contingent purportedly passed through or near Ferne Clyffe on their trip to Fort Kaskaskia in 1778. One hundred years later, the Cherokee reportedly used the area as their hunting range while on their Trail of Tears march.