Sinkhole risk in Ringgold 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: 95%
At or near the surface: 0%
Buried under cover: 95%

What this means before you buy

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

That works out to roughly 507 of Ringgold County's 535 square miles on soluble rock. With about 4,608 residents (9 per square mile), there is effectively nowhere in the county off the soluble rock, town or country. The figures come from 408 map points about 1.1 miles apart, so a pocket smaller than that can be missed or overstated.

Two things to read before deciding: why gypsum and salt move faster than limestone, and why the 95% under cover still counts.

Counties around Ringgold County

The nearest county rated sinkhole country is Jackson County, MO, about 120 miles south. 6 of the 6 closest counties land in the same band, so this is a regional pattern rather than a local quirk.

Worth County, MO 20 mi southwest · 0% at surface
Union County, IA 20 mi north · 0% at surface
Taylor County, IA 24 mi west · 0% at surface
Decatur County, IA 24 mi east · 0% at surface
Harrison County, MO 30 mi southeast · 0% at surface
Adams County, IA 31 mi northwest · 0% at surface

What Ringgold County is built on

The largest mapped soluble unit here is the Kansas City Group (limestone), Late Pennsylvanian-Missouri Series in age, covering about 59% of the county. Next is the Lansing Group at 36%.

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

Ringgold County ranks 82 of 99 in Iowa for soluble rock at the surface, and sits above 0% of US counties on that measure.