SinkholeOdds

Sinkhole risk in Clark County, MO: 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
58%
At or near the surface
0%
Buried under cover
58%

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 293 of Clark County's 505 square miles on soluble rock. With about 6,623 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 298 map points about 1.3 miles apart, so a pocket smaller than that can be missed or overstated.

Worth reading for this county: why gypsum and salt move faster than limestone, and why the 58% under cover still counts.

Counties around Clark County

The nearest county rated sinkhole country is Calhoun County, IL, about 103 miles southeast. 5 of the 6 closest counties land in the same band, so this is a regional pattern rather than a local quirk.

Which formation it is

The largest mapped soluble unit here is the Meramecian Series (limestone), Late Mississippian-Meramecian Series in age, covering about 57% of the county. Next is the Yellow Spring Group at under 1%.

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 Missouri

Clark County ranks 84 of 115 in Missouri for soluble rock at the surface, and sits above 0% of US counties on that measure.