AGE OF DINOSAURS
The park bluffs command the first attention of the visitor. The four prominent hollows one views are ravines cut into an elevated plain. About 200 million years ago, what is now Illinois, was lifted from the sea for the last time and the age of the lizards followed. As the giant dinosaurs flourished, this region was the scene of earth movements that resulted in a dislocation of the rocks, producing the Lincoln Fold.
Thus it happens that one is now in the eastern end of the Lincoln Hills which extend 30 miles from Lincoln County, Missouri, into Jersey County, Illinois. To the north the bedrock was uplifted 50 feet per mile, and pulled down steeply hundreds of feet to the south. At Pere Marquette State Park the Illinois River has cut a section through these folded beds. Rocks dipping at 45 degrees are plainly visible at two places along the foot trail and bridle path to Twin Springs. Here one can climb the Lincoln Fold just to the north of the Nature Museum on the foot trail to Goat Cliff.