Region: Shawnee Hills
Counties: Saline, Hardin, Pope
Manager: Shawnee National Forest (link)
The Shawnee Hills took millions of years to form. The rock formations and cliffs at Garden of the Gods are made of sandstone and are about 320 million years old. Long ago most of Illinois, western Indiana and western Kentucky were covered by a giant inland sea. For millions of years great rivers carried sand and mud to the sea, where it settled along the shoreline. Over time, the weight of the sediments turned them into layers of rock thousands of feet thick. At Garden of the Gods the sediment layers were over 20,000 feet thick or about 4 miles deep. Eventually, a great uplift occurred, raising the inland sea above sea level causing it to fill in with sand and mud. The uplift also fractured the bedrock exposing it to nature’s erosive forces. Since that time, windblown sand, rain and freezing and thawing actions have worn down the layers of sediment creating the beautiful rock formations at Garden of the Gods.