Sinkhole risk in Bryan 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: 18%
At or near the surface: 18%
Buried under cover: 0%

The next step for one property

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 161 of Bryan County's 904 square miles on soluble rock, 161 of them with the rock at or near the surface. With about 50,305 residents (56 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 247 map points about 1.9 miles apart, so a pocket smaller than that can be missed or overstated.

Two things to read before deciding: the signs to look for and how an inspection works, and how these percentages are measured.

Counties around Bryan County

The nearest county rated sinkhole country is Grady County, OK, about 118 miles northwest. 5 of the 6 closest counties land in the same band, so this is a regional pattern rather than a local quirk.

Fannin County, TX 27 mi south · 25% at surface
Marshall County, OK 29 mi west · 35% at surface
Atoka County, OK 32 mi northeast · 5% at surface
Johnston County, OK 33 mi northwest · 33% at surface
Grayson County, TX 33 mi southwest · 36% at surface
Choctaw County, OK 41 mi east · 30% at surface

What Bryan County is built on

The largest mapped soluble unit here is the Caddo Formation (limestone), Early Cretaceous in age, covering about 11% of the county. Next is the Grayson Marl and Bennington Limestone at 3%.

Against the rest of Oklahoma

Bryan County ranks 35 of 77 in Oklahoma for soluble rock at the surface, and sits above 73% of US counties on that measure.