Sinkhole risk in Brantley County, GA: Pockets of it

Pockets of it

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

On soluble rock: 100%
At or near the surface: under 1%
Buried under cover: 100%

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 443 of Brantley County's 443 square miles on soluble rock. With about 18,795 residents (42 per square mile), there is effectively nowhere in the county off the soluble rock, town or country. The figures come from 570 map points about 0.9 miles apart, so a pocket smaller than that can be missed or overstated.

Counties around Brantley County

The nearest county rated sinkhole country is Nassau County, FL, about 43 miles south. 4 of the 6 closest counties land in the same band, so this is a regional pattern rather than a local quirk.

Pierce County, GA 17 mi northwest · 0% at surface
Wayne County, GA 25 mi north · 0% at surface
Ware County, GA 28 mi west · 0% at surface
Camden County, GA 28 mi southeast · under 1% at surface
Glynn County, GA 29 mi east · 0% at surface
Charlton County, GA 30 mi south · 1% at surface

Which formation it is

The largest mapped soluble unit here is the Charlton Formation and Duplin Marl (limestone), Pliocene in age, covering about 100% of the county. Next is the "Hawthorn Formation" at under 1%.

The county also lies over the Floridan shelf, 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 Georgia

Brantley County ranks 73 of 159 in Georgia for soluble rock at the surface, and sits above 50% of US counties on that measure.