Arch Rock

Arch Rock is the most dazzling example of Mackinac Island's breccia formations. It once stood as a solid mass 100 feet above the lake level. About 4,000 years ago the lake waters slowly dissolved the softer material that extended into the center of the formation. As the lake erosion cut away its base, the middle of the stack slowly crumbled into the water leaving the firm breccia limestone arch that we see today.

Mackinac Island, Michigan · United States