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

No soluble rock mapped

No soluble bedrock mapped.

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

The next step for one property

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

That works out to roughly 1 of Passaic County's 186 square miles on soluble rock. With about 526,597 residents (2,829 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 355 map points about 0.7 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 Passaic County

The nearest county rated sinkhole country is Union County, PA, about 144 miles west. 3 of the 6 closest counties land in the same band; the ground changes quickly around here.

Bergen County, NJ 13 mi southeast · 0% at surface
Rockland County, NY 16 mi northeast · 0% at surface
Essex County, NJ 17 mi south · 0% at surface
Morris County, NJ 18 mi southwest · 1% at surface
Sussex County, NJ 22 mi west · 0% at surface
Hudson County, NJ 24 mi southeast · 0% at surface

What Passaic County is built on

The largest mapped soluble unit here is the Berkshire Valley and Poxono Island Formations, undivided (limestone), Upper Silurian in age, covering about under 1% of the county. Next is the Franklin Marble at under 1%.

Against the rest of New Jersey

Passaic County ranks 19 of 21 in New Jersey for soluble rock at the surface, and sits above 0% of US counties on that measure.