The area contains many ridge lines, historical shorelines from the lake's water receding since prehistoric time. The many ridges and swales tell different stories between the plants and animal life. The area is a prime bird watching stop, but the rare fauna, sedges, lilies and wildflowers draw many visitors to the sanctuary. About a dozen endangered or threatened Wisconsin plant species are found in the sanctuary as well as the Federally threatened Dwarf Lake Iris. The Hines Emerald dragonfly, the only dragonfly on the Federal Endangered Species List, is also found at the Ridges. The land was purchased by Door County from the United States government in 1937. During that same year, the nonprofit Ridges Sanctuary formed to protect and maintain the area. The Ridges Sanctuary leases and maintains most of the acreage including two range lighthouses; alignment lights used by ships to enter Bailey's Harbor. Originally lit with lanterns, the beacons are now electric.