Sinkhole risk in Colquitt 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: 21%
Buried under cover: 79%

What to do about a house in Colquitt County

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 547 of Colquitt County's 547 square miles on soluble rock, 113 of them with the rock at or near the surface. With about 46,977 residents (86 per square mile), there is effectively nowhere in the county off the soluble rock, town or country. The figures come from 359 map points about 1.2 miles apart, so a pocket smaller than that can be missed or overstated.

Counties around Colquitt County

The nearest county rated sinkhole country is Mitchell County, GA, about 25 miles west, close enough that the same rock may run under the county line. 5 of the 6 closest counties land in the same band, so this is a regional pattern rather than a local quirk.

Cook County, GA 20 mi east · 16% at surface
Tift County, GA 23 mi northeast · 5% at surface
Thomas County, GA 24 mi south · 34% at surface
Mitchell County, GA 25 mi west · 66% at surface
Worth County, GA 25 mi north · 28% at surface
Brooks County, GA 28 mi southeast · 29% at surface

Which formation it is

The largest mapped soluble unit here is the "Hawthorn Formation" (sand), Miocene in age, covering about 76% of the county. Next is the "Hawthorn Formation" at 21%.

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

Colquitt County ranks 37 of 159 in Georgia for soluble rock at the surface, and sits above 75% of US counties on that measure.