Sinkhole risk in Jones County, IA: Pockets of it

Pockets of it

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

On soluble rock: 100%
At or near the surface: 1%
Buried under cover: 99%

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 574 of Jones County's 576 square miles on soluble rock, 6 of them with the rock at or near the surface. With about 21,116 residents (37 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.

Two things to read before deciding: why the 99% under cover still counts, and the signs to look for and how an inspection works.

Counties around Jones County

The nearest county rated sinkhole country is Jo Daviess County, IL, about 49 miles east. 5 of the 6 closest counties land in the same band, so this is a regional pattern rather than a local quirk.

Cedar County, IA 24 mi south · 0% at surface
Linn County, IA 25 mi west · 0% at surface
Dubuque County, IA 26 mi northeast · 34% at surface
Delaware County, IA 27 mi northwest · 5% at surface
Jackson County, IA 28 mi east · 33% at surface
Clinton County, IA 34 mi southeast · 1% at surface

Which formation it is

The largest mapped soluble unit here is the Niagaran Series (dolostone (dolomite)), Middle Silurian in age, covering about 93% of the county. Next is the Alexandrian Series at 6%.

Against the rest of Iowa

Jones County ranks 12 of 99 in Iowa for soluble rock at the surface, and sits above 55% of US counties on that measure.