Sinkhole risk in Columbus County, NC: Sinkhole country

Sinkhole country

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

On soluble rock: 80%
At or near the surface: 80%
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 753 of Columbus County's 938 square miles on soluble rock, 753 of them with the rock at or near the surface. With about 50,054 residents (53 per square mile), much of the land is open, and the mapped rock may sit far from where people actually live. The figures come from 513 map points about 1.4 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 Columbus County

The closest county with no soluble rock mapped is Chatham County, NC, about 106 miles north. 2 of the 6 closest counties land in the same band; the ground changes quickly around here.

Bladen County, NC 24 mi north · 38% at surface
Brunswick County, NC 28 mi southeast · 30% at surface
Horry County, SC 31 mi southwest · 29% at surface
Robeson County, NC 37 mi northwest · 89% at surface
Marion County, SC 43 mi west · 33% at surface
Dillon County, SC 43 mi west · 79% at surface

Which formation it is

The largest mapped soluble unit here is the Peedee Formation (sand), Cretaceous in age, covering about 59% of the county. Next is the Yorktown Formation and Duplin Formation, Undivided at 21%.

Against the rest of North Carolina

Columbus County ranks 11 of 100 in North Carolina for soluble rock at the surface, and sits above 95% of US counties on that measure.