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.