Sinkhole risk in Fond du Lac County, WI: Pockets of it

Pockets of it

Soluble rock at the surface or under thin cover in part of the county.

On soluble rock: 95%
At or near the surface: 0%
Buried under cover: 95%

What this means before you buy

Check the parcel against your state survey sinkhole map, and ask for an inspection if cracks, depressions or sticking doors show up.

That works out to roughly 681 of Fond du Lac County's 720 square miles on soluble rock. With about 104,269 residents (145 per square mile), there is effectively nowhere in the county off the soluble rock, town or country. The figures come from 315 map points about 1.5 miles apart, so a pocket smaller than that can be missed or overstated.

Counties around Fond du Lac County

The nearest county rated sinkhole country is Iowa County, WI, about 97 miles southwest. 2 of the 6 closest counties land in the same band; the ground changes quickly around here.

Green Lake County, WI 24 mi west · 0% at surface
Winnebago County, WI 24 mi north · under 1% at surface
Dodge County, WI 25 mi southwest · 0% at surface
Calumet County, WI 26 mi northeast · 0% at surface
Washington County, WI 28 mi southeast · 0% at surface
Ozaukee County, WI 37 mi southeast · 0% at surface

Which formation it is

The largest mapped soluble unit here is the Sinnipee Group (dolostone (dolomite)), Ordovician in age, covering about 46% of the county. Next is the Silurian, undivided at 39%.

Against the rest of Wisconsin

Fond du Lac County ranks 37 of 72 in Wisconsin for soluble rock at the surface, and sits above 0% of US counties on that measure.