Sinkhole risk in Wake County, NC: 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: 8%
At or near the surface: 8%
Buried under cover: 0%

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 69 of Wake County's 835 square miles on soluble rock, 69 of them with the rock at or near the surface. With about 1,232,444 residents (1,476 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 545 map points about 1.2 miles apart, so a pocket smaller than that can be missed or overstated.

Worth reading for this county: how these percentages are measured, and the warning signs that apply anywhere.

Counties around Wake County

The nearest county rated sinkhole country is Harnett County, NC, about 32 miles southwest, close enough that the same rock may run under the county line. None of the 6 closest counties land in the same band, so Wake County stands out from its surroundings.

Durham County, NC 21 mi northwest · 0% at surface
Johnston County, NC 25 mi southeast · 38% at surface
Franklin County, NC 29 mi northeast · 0% at surface
Harnett County, NC 32 mi southwest · 60% at surface
Orange County, NC 32 mi northwest · 0% at surface
Chatham County, NC 34 mi west · 0% at surface

The rock underneath

The largest mapped soluble unit here is the Middendorf Formation (sand), Cretaceous in age, covering about 8% of the county.

Against the rest of North Carolina

Wake County ranks 43 of 100 in North Carolina for soluble rock at the surface, and sits above 66% of US counties on that measure.