Sinkhole risk in Crawford County, WI: Sinkhole country

Sinkhole country

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

On soluble rock: 81%
At or near the surface: 71%
Buried under cover: 10%

What this means before you buy

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

That works out to roughly 462 of Crawford County's 571 square miles on soluble rock, 405 of them with the rock at or near the surface. With about 16,008 residents (28 per square mile), much of the land is open, and the mapped rock may sit far from where people actually live. The figures come from 290 map points about 1.4 miles apart, so a pocket smaller than that can be missed or overstated.

Counties around Crawford County

The closest county with no soluble rock mapped is Juneau County, WI, about 63 miles northeast. 3 of the 6 closest counties land in the same band; the ground changes quickly around here.

Allamakee County, IA 23 mi west · 25% at surface
Vernon County, WI 25 mi north · 63% at surface
Richland County, WI 27 mi east · 41% at surface
Grant County, WI 28 mi southeast · 84% at surface
Clayton County, IA 34 mi southwest · 54% at surface
Houston County, MN 41 mi northwest · 28% at surface

The rock underneath

The largest mapped soluble unit here is the Prairie du Chien Group (shale), Lower Ordovician in age, covering about 42% of the county. Next is the Ancell Group at 20%.

Against the rest of Wisconsin

Crawford County ranks 4 of 72 in Wisconsin for soluble rock at the surface, and sits above 93% of US counties on that measure.