The Dells of the Wisconsin River encompasses over 5 miles of Wisconsin River corridor with a spectacular gorge, cliffs, tributary canyons, and rock formations carved into Cambrian sandstone. Formed between 510-520 million years ago, some cliffs rise over one hundred feet above the water and have been shaped by the erosive processes of water and wind. With a variety of exposures and moisture regimes, the cliffs afford many different niches for plants, some of which are very rare in Wisconsin. Cliff cudweed (Gnaphalium obtusifolium var saxicola), known from only 2 places on Earth - here and in the Kickapoo Valley, grows on protected rock ledges. Other rarities include Lapland azalea (Rhododendron lapponicum), round-stemmed false foxglove (Agalinis gattingeri), maidenhair spleenwort (Asplenium trichomanes), and fragrant fern (Dryopteris fragrans). This area contains a mosaic of plant communities including northern and southern oak/pine forests, oak savanna, and moist and dry cliffs. Rare animals include six dragonfly species including the Royal river cruiser (Macromia taeniolata), six rare mussels and numerous birds. While set aside to protect the rare plants and animals, the Dells also has an important cultural history that spans several thousand years. Various Native Americans, ranging from early Paleo-Indian people to the more recent Ho-Chunk, Sac, and Menominee, were attracted to the scenic waterway, and left behind archeological evidence such as effigy and burial mounds, camps and village sites, garden beds and rock art. Dells of the Wisconsin is owned by the DNR and was designated a State Natural Area in 1994.