Sinkhole risk in Robeson County, NC: Sinkhole country

Sinkhole country

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

On soluble rock: 89%
At or near the surface: 89%
Buried under cover: 0%

What to do about a house in Robeson County

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

That works out to roughly 843 of Robeson County's 947 square miles on soluble rock, 843 of them with the rock at or near the surface. With about 118,624 residents (125 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 573 map points about 1.3 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 Robeson County

The closest county with no soluble rock mapped is Chatham County, NC, about 74 miles north. 4 of the 6 closest counties land in the same band, so this is a regional pattern rather than a local quirk.

Dillon County, SC 23 mi southwest · 79% at surface
Scotland County, NC 25 mi northwest · 91% at surface
Hoke County, NC 27 mi north · 83% at surface
Bladen County, NC 32 mi east · 38% at surface
Cumberland County, NC 32 mi northeast · 23% at surface
Marlboro County, SC 33 mi west · 64% at surface

What Robeson County is built on

The largest mapped soluble unit here is the Black Creek Formation (clay or mud), Cretaceous in age, covering about 61% of the county. Next is the Yorktown Formation and Duplin Formation, Undivided at 26%.

Against the rest of North Carolina

Robeson County ranks 5 of 100 in North Carolina for soluble rock at the surface, and sits above 96% of US counties on that measure.