One of the oldest sites to appear on maps of the western Great Lakes region is the “Dalles” of the Wisconsin River. It was identified as a convenient reference point by French explorers in the 1700’s. The name stuck after the French explorers left Wisconsin, with the spelling and pronunciation Anglicized as the “dells”.
During the Cambrian Period, this community was the sandy shore of an ancient sea. Over time, the sand was compacted, and percolating groundwater cemented the sand into rock. That rock went virtually untouched for years.
Fast forward to when a glacier extended to within four miles east of the area, never touching the Dells. That glacier melted and formed Glacial Lake Wisconsin, a lake about the size of Utah's Great Salt Lake and as deep as 150 feet. The last ice that held back the waters of Glacial Lake Wisconsin began to melt. The failed ice dam unleashed a catastrophic flood; the lake's depth dropped to 50 feet. The meltwaters cut deep, narrow gorges and unusual rock formations into the sandstone and formed the steep-sided canyons and bluffs you see today lining the Wisconsin River. The flood most likely cut the gorges in the Dells in a matter of days or weeks as the swift water eroded away the soft sandstone.
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. 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. One species, (Cliff cudweed (Gnaphalium obtusifolium var saxicola), is known from only 2 places on Earth - here and in the Kickapoo Valley, and grows on protected rock ledges. Other rarities are also present. 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, 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. The privately-owned Louis’ Bluff Unit marks the northern-most extent of the Cambrian sandstone formations of the Dells. The bluff rises more than 200' above the valley floor. Southern Dry-Mesic Forest and Northern Dry-Mesic Forest dominates the side of the bluff, with floodplain forest at its base. Also present is a pine relict community. A small dry prairie remnant is found at the top of the bluff. Exposed and shaded sandstone cliffs provide habitat for a diversity of vascular plants and bryophytes. Dells of the Wisconsin is owned by the DNR and was designated a State Natural Area in 1994.
