The Arch Rock on Mackinac Island.

This is a picture of the Arch Rock which is a geologic formation on Mackinac Island in Michigan. It is a natural limestone arch formed during the Nipissing post-glacial period, a period of high Lake Huron levels following the end of the Wisconsin glaciation. To this day Arch Rock stands on the Lake Huron shoreline 146 feet (45 m) above the water. The Native Americans saw Arch Rock as a place of numinous power, and told many stories and legends about it. Today Arch Rock is a focus of Mackinac Island tourism with several trails and paved roads, including the aptly named Arch Rock Road and Arch Rock Bicycle Trail, lead to the formation.