- Natural areas
- Contact information
- For information on State Natural Areas, contact:
- Thomas Meyer
Natural areas conservation biologist
Wisconsin State Natural Areas Program Oakfield Ledge (No. 190)
Fond du Lac County. T14N-R16E, Sections 23, 27, 28, 33. 208 acres.
Oakfield Ledge is one of the most significant exposures of the Niagara Escarpment in Wisconsin, a 650-mile long ridge that runs north from Waukesha County, forms the spine of the Door peninsula, then arcs east through Ontario and ends at Niagara Falls in New York. Located along Horicon Marsh, the hard, erosion resistant Niagara dolomite walls form a series of prominent rock cliffs 40' high - what locals call "the ledge". Deep crevices have formed along fractures in the bedrock. The vegetation of the shaded cliff and boulder strewn steep slope is the most undisturbed and consists of basswood, sugar maple, slippery elm, rock elm, mountain maple, and shagbark hickory. Groundcover includes extensive patches of Canada yew and the shaded cliffs provide habitat for walking, cliff brake, and fragile ferns while more open sites contain the rare rock whitlow-grass (Draba arabisans). Spring seeps provide a moist forest floor habitat for interrupted fern, wild sarsaparilla and pale-flowered leafcup and small creeks with mud bottoms contain great blue lobelia, and swamp saxifrage. Oakfield Ledge is owned by the DNR and was designated a State Natural Area in 1983.
Access: From the intersection of County Highways B and Y south of Oakfield, go south on B 3.2 miles, then east on Breakneck Road 0.6 mile to a parking area at the top of hill.
Visitation Guidelines: Oakfield Ledge is open daily 6:00 a.m. - 8:00 p.m. Food and beverage are not allowed in the natural area.
Oakfield Ledge is owned by:
The DNR's state natural areas program is comprised of lands owned by the state, private conservation organizations, municipalities, other governmental agencies, educational institutions and private individuals. While the majority of SNAs are open to the public, access may vary according to individual ownership policies. Public use restrictions may apply due to public safety, or to protect endangered or threatened species or unique natural features. Lands may be temporarily closed due to specific management activities. Users are encouraged to contact the landowner for more specific details.
The data shown on these maps have been obtained from various sources, and are of varying age, reliability, and resolution. The data may contain errors or omissions and should not be interpreted as a legal representation of legal ownership boundaries.
Manage the site as a reserve for oak opening and moist cliff, as a significant geological and archaeological site, and as an ecological reference area. Natural processes will determine the structure of the site's natural communities, along with prescribed understory manipulation in the savanna (see below). Provide opportunities for research and education on the highest quality native oak openings and moist cliffs.
The native moist cliff species are managed passively, allowing nature to determine their ecological characteristics. The native dominant savanna tree species (primarily oaks) are managed passively. However, some thinning of the canopy, understory manipulation and shrub control via harvest, brushing or fire may be needed to mimic natural disturbance patterns. Augmentation of the ground layer will only add species that historically would have been found on the site, using seeds or plugs from local genetic material; this usually occurs in the early stages of restoration. The mostly passive canopy management and understory manipulation will determine the ecological characteristics of the savanna. Other allowable activities across the entire site include control of invasive plants and animals, maintenance of existing facilities, and access to suppress wildfires. Salvage of trees after a major wind event can occur if the volume of woody material inhibits fire prescriptions.
- The petroglyphs are protected and managed according to Department policy and existing state and federal legislation relating to archaeological sites.
- Roadside easement area may be managed sporadically by township and county.
Very few State Natural Areas have public facilities, but nearly all are open for a variety of recreational activities as indicated below. Generally, there are no picnic areas, restrooms, or other developments. Parking lots or designated parking areas are noted on individual SNA pages and maps. Trails, if present, are typically undesignated footpaths. If a developed trail is present, it will normally be noted on the SNA map and/or under the "Access" tab. A compass and topographic map or a GPS unit are useful tools for exploring larger, isolated SNAs.
In general, the activities listed below are allowed on all DNR-owned SNA lands. Exceptions to this list of public uses, such as SNAs closed to hunting, are noted under the "Access" tab above and posted with signs on site.
- Cross country skiing
- Horseback riding
- Rock climbing
- Vehicles, including bicycles, ATVs, aircraft, and snowmobiles except on trails and roadways designated for their use
- Collecting of animals, non-edible fungi, rocks, minerals, fossils, archaeological artifacts, soil, downed wood, or any other natural material, alive or dead. Collecting for scientific research requires a permit issued by the DNR
- Collecting of plants including seeds, roots or other non-edible parts of herbaceous plants such as wildflowers or grasses
- Camping and campfires
For rules governing state-owned SNAs and other state lands, please consult Chapter NR 45 Wis. Admin. Code [exit DNR]