Sinkhole risk in Jo Daviess County, IL: Sinkhole country

Sinkhole country

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

On soluble rock: 71%
At or near the surface: 58%
Buried under cover: 14%

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 428 of Jo Daviess County's 601 square miles on soluble rock, 347 of them with the rock at or near the surface. With about 21,528 residents (36 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 300 map points about 1.4 miles apart, so a pocket smaller than that can be missed or overstated.

Two things to read before deciding: why the 14% under cover still counts, and the signs to look for and how an inspection works.

Counties around Jo Daviess County

The closest county with no soluble rock mapped is Stark County, IL, about 90 miles south. 1 of the 6 closest counties land in the same band; the ground changes quickly around here.

Lafayette County, WI 21 mi north · 91% at surface
Jackson County, IA 23 mi southwest · 33% at surface
Carroll County, IL 25 mi southeast · 11% at surface
Stephenson County, IL 28 mi east · 3% at surface
Dubuque County, IA 35 mi west · 34% at surface
Clinton County, IA 36 mi southwest · 1% at surface

The rock underneath

The largest mapped soluble unit here is the Galena-Platteville Groups (limestone), Ordovician in age, covering about 55% of the county. Next is the Silurian at 15%.

Against the rest of Illinois

Jo Daviess County ranks 2 of 102 in Illinois for soluble rock at the surface, and sits above 89% of US counties on that measure.