Sinkhole risk in Brunswick County, NC: Pockets of it

Pockets of it

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

On soluble rock: 30%
At or near the surface: 30%
Buried under cover: under 1%

What to do about a house in Brunswick County

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 258 of Brunswick County's 849 square miles on soluble rock, 257 of them with the rock at or near the surface. With about 167,112 residents (197 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 608 map points about 1.2 miles apart, so a pocket smaller than that can be missed or overstated.

Counties around Brunswick County

The nearest county rated sinkhole country is New Hanover County, NC, about 23 miles northeast, 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.

New Hanover County, NC 23 mi northeast · 79% at surface
Columbus County, NC 28 mi northwest · 80% at surface
Pender County, NC 38 mi northeast · 89% at surface
Bladen County, NC 42 mi northwest · 38% at surface
Horry County, SC 44 mi west · 29% at surface
Duplin County, NC 64 mi north · 93% at surface

Which formation it is

The largest mapped soluble unit here is the Peedee Formation (sand), Cretaceous in age, covering about 30% of the county. Next is the Castle Hayne Formation; Comfort Member and New Hanover Member, undivided at under 1%.

Against the rest of North Carolina

Brunswick County ranks 29 of 100 in North Carolina for soluble rock at the surface, and sits above 79% of US counties on that measure.