SinkholeOdds

Sinkhole risk in Adair County, IA: Mostly deep or small

Mostly deep or small

Some soluble rock, mostly deeply buried or in a small share of the county.

On soluble rock
79%
At or near the surface
0%
Buried under cover
79%

The next step for one property

Sinkholes are uncommon here; watch for new depressions after heavy rain or leaking pipes.

That works out to roughly 450 of Adair County's 569 square miles on soluble rock. With about 7,431 residents (13 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 391 map points about 1.2 miles apart, so a pocket smaller than that can be missed or overstated.

Read next: why gypsum and salt move faster than limestone, and why the 79% under cover still counts.

Counties around Adair County

The nearest county rated sinkhole country is Jackson County, MO, about 161 miles south. 6 of the 6 closest counties land in the same band, so this is a regional pattern rather than a local quirk.

What Adair County is built on

The largest mapped soluble unit here is the Shawnee Group (limestone), Late Pennsylvanian-Virgil Series in age, covering about 45% of the county. Next is the Kansas City Group at 19%.

The county also lies over the Forest City Basin, a deep salt or gypsum basin. Deep beds rarely cause surface collapse on their own, but wells and mining into them have.

Against the rest of Iowa

Adair County ranks 14 of 99 in Iowa for soluble rock at the surface, and sits above 0% of US counties on that measure.