Sinkhole risk in Columbia County, GA: Mostly deep or small

Mostly deep or small

Some soluble rock, mostly deeply buried or in a small share of the county.

On soluble rock: 16%
At or near the surface: 10%
Buried under cover: 7%

What this means before you buy

Sinkholes are uncommon here; watch for new depressions after heavy rain or leaking pipes.

That works out to roughly 47 of Columbia County's 290 square miles on soluble rock, 28 of them with the rock at or near the surface. With about 167,472 residents (577 per square mile), most of the county is built up, so a mapped unit is likely to sit under somebody's street. The figures come from 569 map points about 0.7 miles apart, so a pocket smaller than that can be missed or overstated.

Counties around Columbia County

The nearest county rated sinkhole country is Aiken County, SC, about 36 miles east, close enough that the same rock may run under the county line. 1 of the 6 closest counties land in the same band; the ground changes quickly around here.

McDuffie County, GA 14 mi west · 22% at surface
Richmond County, GA 17 mi southeast · 31% at surface
Lincoln County, GA 20 mi northwest · 0% at surface
Edgefield County, SC 23 mi northeast · 24% at surface
McCormick County, SC 24 mi north · 0% at surface
Warren County, GA 26 mi west · 3% at surface

Which formation it is

The largest mapped soluble unit here is the Lower Tertiary-Cretaceous undifferentiated (sand), Lower Tertiary-Cretaceous in age, covering about 16% of the county.

Against the rest of Georgia

Columbia County ranks 46 of 159 in Georgia for soluble rock at the surface, and sits above 68% of US counties on that measure.