Sinkhole risk in Lafayette County, WI: Sinkhole country

Sinkhole country

Soluble rock at or near the surface across much of the county.

On soluble rock: 99%
At or near the surface: 91%
Buried under cover: 7%

The next step for one property

Get a sinkhole or geotechnical inspection before buying, building or adding weight to a foundation.

That works out to roughly 624 of Lafayette County's 634 square miles on soluble rock, 577 of them with the rock at or near the surface. With about 17,306 residents (27 per square mile), there is effectively nowhere in the county off the soluble rock, town or country. The figures come from 392 map points about 1.3 miles apart, so a pocket smaller than that can be missed or overstated.

Two things to read before deciding: why the 7% under cover still counts, and the signs to look for and how an inspection works.

Counties around Lafayette County

The closest county with no soluble rock mapped is Juneau County, WI, about 88 miles north. 3 of the 6 closest counties land in the same band; the ground changes quickly around here.

Jo Daviess County, IL 21 mi south · 58% at surface
Iowa County, WI 24 mi north · 77% at surface
Green County, WI 27 mi east · 38% at surface
Stephenson County, IL 32 mi southeast · 3% at surface
Grant County, WI 32 mi northwest · 84% at surface
Dubuque County, IA 40 mi west · 34% at surface

The rock underneath

The largest mapped soluble unit here is the Sinnipee Group (dolostone (dolomite)), Ordovician in age, covering about 81% of the county. Next is the Ancell Group at 12%.

Against the rest of Wisconsin

Lafayette County ranks 1 of 72 in Wisconsin for soluble rock at the surface, and sits above 97% of US counties on that measure.