Arch Rock on Mackinac Island, Michigan
February 23, 2012
Photographer: Chloe Cook; Mona Shores Public Schools
Summary Author: Matthew L. Schuchardt; Chloe Cook
Pictured above is Arch Rock on Mackinac Island, Michigan. Arch Rock is a natural limestone/breccia formation on the shoreline of Lake Huron, standing 146 ft (45 m) above the lake level. It's believed to have formed about 5,000 years ago during the Nipissing stage of high water levels on Lake Huron. Limestone/breccia formations are rather unusual in the Great Lakes region, although the arch is one of several such formations on Mackinac Island -- others include Sugar Loaf and Skull Cave. Northern white cedars (Thuja occidentalis) have taken hold in the rocky crevasses below the arch. Photo taken in June of 2009.