Sinkhole risk in Effingham 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: 18%
Buried under cover: 82%

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 477 of Effingham County's 479 square miles on soluble rock, 87 of them with the rock at or near the surface. With about 73,148 residents (153 per square mile), there is effectively nowhere in the county off the soluble rock, town or country. The figures come from 597 map points about 0.9 miles apart, so a pocket smaller than that can be missed or overstated.

Two things to read before deciding: why the 82% under cover still counts, and the signs to look for and how an inspection works.

Counties around Effingham County

The nearest county rated sinkhole country is Hampton County, SC, about 31 miles north, close enough that the same rock may run under the county line. 4 of the 6 closest counties land in the same band, so this is a regional pattern rather than a local quirk.

Jasper County, SC 19 mi east · 21% at surface
Bulloch County, GA 23 mi west · 13% at surface
Bryan County, GA 24 mi south · under 1% at surface
Chatham County, GA 30 mi southeast · 0% at surface
Screven County, GA 31 mi northwest · 5% at surface
Hampton County, SC 31 mi north · 70% at surface

The rock underneath

The largest mapped soluble unit here is the "Hawthorn Formation" (sand), Miocene in age, covering about 52% of the county. Next is the Charlton Formation and Duplin Marl at 28%.

Against the rest of Georgia

Effingham County ranks 38 of 159 in Georgia for soluble rock at the surface, and sits above 73% of US counties on that measure.