SinkholeOdds

Sinkhole risk in Clark County, AR: Pockets of it

Pockets of it

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

On soluble rock
21%
At or near the surface
21%
Buried under cover
0%

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 178 of Clark County's 866 square miles on soluble rock, 178 of them with the rock at or near the surface. With about 20,920 residents (24 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 262 map points about 1.8 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 the signs to look for and how an inspection works.

Counties around Clark County

The nearest county rated sinkhole country is Adair County, OK, about 152 miles northwest. 1 of the 6 closest counties land in the same band; the ground changes quickly around here.

Which formation it is

The largest mapped soluble unit here is the Nacatoch Sand (sand), Late Cretaceous in age, covering about 5% of the county. Next is the Arkadelphia Marl at 5%.

The county also lies over the Gulf Coast salt domes, 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 Arkansas

Clark County ranks 24 of 75 in Arkansas for soluble rock at the surface, and sits above 75% of US counties on that measure.