Sinkhole risk in Sussex 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: 24%
At or near the surface: 0%
Buried under cover: 24%

What to do about a house in Sussex County

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

That works out to roughly 124 of Sussex County's 518 square miles on soluble rock. With about 147,444 residents (284 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 545 map points about 1.0 miles apart, so a pocket smaller than that can be missed or overstated.

Worth reading for this county: why the 24% under cover still counts, and how these percentages are measured.

Counties around Sussex County

The nearest county rated sinkhole country is Union County, PA, about 124 miles west. 3 of the 6 closest counties land in the same band; the ground changes quickly around here.

Morris County, NJ 21 mi south · 1% at surface
Passaic County, NJ 22 mi east · 0% at surface
Pike County, PA 22 mi northwest · 0% at surface
Warren County, NJ 26 mi southwest · 10% at surface
Orange County, NY 27 mi northeast · 0% at surface
Essex County, NJ 34 mi southeast · 0% at surface

Which formation it is

The largest mapped soluble unit here is the Allentown Dolomite (dolostone (dolomite)), Lower Ordovician and Upper Cambrian in age, covering about 9% of the county. Next is the Beekmantown Group, Lower Part at 4%.

Against the rest of New Jersey

Sussex County ranks 20 of 21 in New Jersey for soluble rock at the surface, and sits above 0% of US counties on that measure.