Sinkhole risk in Choctaw County, OK: Pockets of it

Pockets of it

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

On soluble rock: 30%
At or near the surface: 30%
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 227 of Choctaw County's 770 square miles on soluble rock, 227 of them with the rock at or near the surface. With about 14,174 residents (18 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 342 map points about 1.5 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 the signs to look for and how an inspection works.

Counties around Choctaw County

The nearest county rated sinkhole country is Cherokee County, OK, about 133 miles north. 2 of the 6 closest counties land in the same band; the ground changes quickly around here.

Lamar County, TX 25 mi south · 7% at surface
Pushmataha County, OK 26 mi north · 0% at surface
Atoka County, OK 37 mi northwest · 5% at surface
Red River County, TX 40 mi southeast · 8% at surface
Bryan County, OK 41 mi west · 18% at surface
Fannin County, TX 44 mi southwest · 25% at surface

The rock underneath

The largest mapped soluble unit here is the Caddo Formation (limestone), Early Cretaceous in age, covering about 9% of the county. Next is the Kiamichi Formation at 8%.

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 Oklahoma

Choctaw County ranks 30 of 77 in Oklahoma for soluble rock at the surface, and sits above 79% of US counties on that measure.