Sinkhole risk in Barnwell County, SC: Pockets of it

Pockets of it

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

On soluble rock: 99%
At or near the surface: 45%
Buried under cover: 54%

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 542 of Barnwell County's 548 square miles on soluble rock, 245 of them with the rock at or near the surface. With about 20,495 residents (37 per square mile), there is effectively nowhere in the county off the soluble rock, town or country. The figures come from 242 map points about 1.5 miles apart, so a pocket smaller than that can be missed or overstated.

Counties around Barnwell County

The nearest county rated sinkhole country is Allendale County, SC, about 20 miles south, close enough that the same rock may run under the county line. 2 of the 6 closest counties land in the same band; the ground changes quickly around here.

Allendale County, SC 20 mi south · 76% at surface
Bamberg County, SC 22 mi east · 84% at surface
Aiken County, SC 23 mi northwest · 68% at surface
Burke County, GA 36 mi southwest · 3% at surface
Screven County, GA 37 mi south · 5% at surface
Hampton County, SC 37 mi southeast · 70% at surface

What Barnwell County is built on

The largest mapped soluble unit here is the Huber/Lisbon/Barnwell Formations, undivided (sand), Eocene in age, covering about 98% of the county. Next is the Duplin Formation at under 1%.

Against the rest of South Carolina

Barnwell County ranks 19 of 46 in South Carolina for soluble rock at the surface, and sits above 86% of US counties on that measure.