Sinkhole risk in Dillon County, SC: Sinkhole country

Sinkhole country

Soluble rock at or near the surface across much of the county.

On soluble rock: 79%
At or near the surface: 79%
Buried under cover: 0%

What this means before you buy

Get a sinkhole or geotechnical inspection before buying, building or adding weight to a foundation.

That works out to roughly 318 of Dillon County's 405 square miles on soluble rock, 318 of them with the rock at or near the surface. With about 27,577 residents (68 per square mile), homes are spread across towns and farmland, and a mapped unit may or may not reach the developed parts. The figures come from 487 map points about 0.9 miles apart, so a pocket smaller than that can be missed or overstated.

Worth reading for this county: the signs to look for and how an inspection works, and how these percentages are measured.

Counties around Dillon County

The closest county with no soluble rock mapped is Union County, NC, about 78 miles northwest. 5 of the 6 closest counties land in the same band, so this is a regional pattern rather than a local quirk.

Marion County, SC 21 mi south · 33% at surface
Marlboro County, SC 23 mi northwest · 64% at surface
Robeson County, NC 23 mi northeast · 89% at surface
Florence County, SC 31 mi southwest · 77% at surface
Scotland County, NC 32 mi north · 91% at surface
Darlington County, SC 34 mi west · 87% at surface

Which formation it is

The largest mapped soluble unit here is the Bear Bluff Formation (sand), Pliocene in age, covering about 52% of the county. Next is the Duplin Formation at 22%.

Against the rest of South Carolina

Dillon County ranks 5 of 46 in South Carolina for soluble rock at the surface, and sits above 94% of US counties on that measure.