Sinkhole risk in Somerset County, NJ: No soluble rock mapped

No soluble rock mapped

No soluble bedrock mapped.

On soluble rock: under 1%
At or near the surface: under 1%
Buried under cover: 0%

What to do about a house in Somerset County

No soluble bedrock is mapped here, so natural sinkholes are unlikely. Collapses from broken pipes or old mines are a separate risk.

Across 302 square miles, under one square mile of Somerset County maps onto soluble rock. With about 357,467 residents (1,184 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 602 map points about 0.7 miles apart, so a pocket smaller than that can be missed or overstated.

Counties around Somerset County

The nearest county rated sinkhole country is Union County, PA, about 130 miles west. 4 of the 6 closest counties land in the same band, so this is a regional pattern rather than a local quirk.

Middlesex County, NJ 14 mi southeast · 0% at surface
Hunterdon County, NJ 15 mi west · 5% at surface
Union County, NJ 18 mi east · 0% at surface
Mercer County, NJ 20 mi south · 0% at surface
Morris County, NJ 21 mi north · 1% at surface
Essex County, NJ 25 mi northeast · 0% at surface

The rock underneath

The largest mapped soluble unit here is the Passaic Formation Limestone-clast Conglomerate facies (conglomerate), Lower Jurassic and Upper Triassic in age, covering about under 1% of the county. Next is the Leithsville Formation at under 1%.

Against the rest of New Jersey

Somerset County ranks 10 of 21 in New Jersey for soluble rock at the surface, and sits above 51% of US counties on that measure.