Sinkhole risk in Hunterdon County, NJ: 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: 5%
At or near the surface: 5%
Buried under cover: under 1%

The next step for one property

Sinkholes are uncommon here; watch for new depressions after heavy rain or leaking pipes.

That works out to roughly 21 of Hunterdon County's 428 square miles on soluble rock, 20 of them with the rock at or near the surface. With about 131,708 residents (308 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 587 map points about 0.9 miles apart, so a pocket smaller than that can be missed or overstated.

Two things to read before deciding: how these percentages are measured, and the warning signs that apply anywhere.

Counties around Hunterdon County

The nearest county rated sinkhole country is Union County, PA, about 115 miles west. 3 of the 6 closest counties land in the same band; the ground changes quickly around here.

Somerset County, NJ 15 mi east · under 1% at surface
Bucks County, PA 19 mi southwest · 2% at surface
Warren County, NJ 21 mi north · 10% at surface
Mercer County, NJ 22 mi southeast · 0% at surface
Northampton County, PA 24 mi northwest · 33% at surface
Morris County, NJ 28 mi northeast · 1% at surface

The rock underneath

The largest mapped soluble unit here is the Allentown Dolomite (dolostone (dolomite)), Lower Ordovician and Upper Cambrian in age, covering about 2% of the county. Next is the Leithsville Formation at 1%.

Against the rest of New Jersey

Hunterdon County ranks 6 of 21 in New Jersey for soluble rock at the surface, and sits above 62% of US counties on that measure.