Caribou Arch, Isle Royale, Michigan
Photo by Mary Drew
NABSQNO 16U-383650-5328200. Caribou Arch is a sea natural arch eroded through an outdrop of Copper Harbour conglomerate, a group within the Keweenawan Supergroup. The arch was formed by wave action by the waters of Lake Superior.
Caribou Arch is located on the southeast shore of West Caribou Island, Isle Royale, Michigan. Access is usually by boat. Note that Isle Royale National Park is closed in winter. The arch has a span of about 12 feet.