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Observatory Hill

No. 223


Photo by Thomas A. Meyer/DNR


The highest point in Marquette County is Observatory Hill, an isolated outcropping of porphyritic rhyolite rising 300 feet above the surrounding landscape. The fine-grained rhyolite, an igneous rock embedded with feldspar crystals, is highly resistant to erosion and has been dated to 1.76 billion years ago. On the exposed rocks at the summit are polished rock surfaces with grooves, striations, and chatter marks created by the passage of the glacial Cary ice sheet 12,000 years ago.

Recently, scientists have discovered the existence of petroglyphs on the hill’s rock outcroppings, which may be part of a larger prehistoric petroform found in Marquette County. The slopes are covered with a southern dry forest community dominated by red and white oak, basswood and shagbark hickory and much of the area is now being restored to oak savanna – an imperiled vegetation community in Wisconsin.

Near the top of the hill, bedrock is exposed or close to the surface creating acidic conditions where a specialized glade community has developed. Red cedar dominates the glade and the thin soils support a sparse ground cover of mosses, ferns, and lichens. The hill has long been known by naturalists and was a favorite childhood haunt of John Muir who lived nearby. Observatory Hill is owned by the DNR and was designated a State Natural Area in 1989.

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. If a developed trail is present, it will normally be noted on the SNA map and/or under the Maps tab. A compass and topographic map or a GPS unit are useful tools for exploring larger, isolated SNAs.

The good majority of SNAs are isolated and have few or no facilities. Some SNAs have vehicle access lanes or parking lots, but their accessibility may vary depending on weather conditions. Parking lots and lanes are not plowed during winter. Hiking trails may be nonexistent or consist of undeveloped footpaths. A GPS unit or compass and a detailed topographic map are useful tools for exploring larger SNAs.

Hunting and trapping

This SNA has multiple landowners: Opportunities for hunting and trapping depend on the landowner. In general, most DNR-owned land allows hunting and trapping. Partner-owned land may have other rules (for example, university-owned lands do not allow hunting or trapping). Please contact them directly to find out about their rules for hunting and trapping. You can find a link to other owner websites under the Resources tab.
Note: There is a planned timber harvest being conducted as part of a long-term oak savanna restoration. See the flyer for more information.

Allowable activities: DNR-owned land

The activities listed below are generally allowed on all DNR-owned SNA lands. Exceptions to this list of public uses, such as SNAs closed to hunting, are noted above and posted with signs on the property site.

Prohibited activities: all SNAs

  • Camping and campfires
  • Collecting of animals (other than legally harvested species), 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
  • Geocaching
  • Horseback riding
  • Rock climbing
  • Vehicles, including bicycles, ATVs, aircraft, and snowmobiles except on trails and roadways designated for their use.

For rules governing state-owned SNAs and other state lands, please consult Chapter NR 45 Wis. Admin. Code [exit DNR].


Marquette County. T14N-R10E, Section 8. 208 acres.

Driving directions

From the intersection of Highways 22 and F on the south side of Montello, go south on F for 4.8 miles, then east on 14th Road for 0.5 miles, then south on 13th Road for 1.4 miles, then east on Gillette Avenue for 0.6 miles to a parking area north of the road. A footpath to the summit begins at the northwest corner of the old field.

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. To create your custom map where you can zoom to a specific location, please use the DNR's Mapping Application.

Property Map [PDF]

Observatory Hill is owned by: The Wisconsin DNR and Private

Management objectives and prescriptions