Sinkhole risk in Green 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: 99%
At or near the surface: 38%
Buried under cover: 61%

What to do about a house in Green County

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 578 of Green County's 584 square miles on soluble rock, 223 of them with the rock at or near the surface. With about 37,183 residents (64 per square mile), there is effectively nowhere in the county off the soluble rock, town or country. The figures come from 391 map points about 1.2 miles apart, so a pocket smaller than that can be missed or overstated.

Counties around Green County

The nearest county rated sinkhole country is Lafayette County, WI, about 27 miles west, close enough that the same rock may run under the county line. 3 of the 6 closest counties land in the same band; the ground changes quickly around here.

Stephenson County, IL 23 mi south · 3% at surface
Lafayette County, WI 27 mi west · 91% at surface
Rock County, WI 27 mi east · 0% at surface
Dane County, WI 29 mi north · 19% at surface
Winnebago County, IL 33 mi southeast · 5% at surface
Iowa County, WI 35 mi northwest · 77% at surface

What Green County is built on

The largest mapped soluble unit here is the Sinnipee Group (dolostone (dolomite)), Ordovician in age, covering about 54% of the county. Next is the Ancell Group at 37%.

Against the rest of Wisconsin

Green County ranks 7 of 72 in Wisconsin for soluble rock at the surface, and sits above 83% of US counties on that measure.