Sinkhole risk in Burlington 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: 4%
At or near the surface: 4%
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 34 of Burlington County's 799 square miles on soluble rock, 34 of them with the rock at or near the surface. With about 475,515 residents (595 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 553 map points about 1.2 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 Burlington County

The nearest county rated sinkhole country is Union County, PA, about 147 miles northwest. 3 of the 6 closest counties land in the same band; the ground changes quickly around here.

Camden County, NJ 17 mi west · 6% at surface
Ocean County, NJ 21 mi east · 1% at surface
Philadelphia County, PA 27 mi west · 0% at surface
Gloucester County, NJ 28 mi west · 9% at surface
Atlantic County, NJ 28 mi south · 0% at surface
Mercer County, NJ 28 mi north · 0% at surface

What Burlington County is built on

The largest mapped soluble unit here is the Vincentown Formation (sand), upper Paleocene, Selandian in age, covering about 3% of the county. Next is the Mt. Laurel Formation at under 1%.

Against the rest of New Jersey

Burlington County ranks 7 of 21 in New Jersey for soluble rock at the surface, and sits above 62% of US counties on that measure.