Sinkhole risk in Beaver County, PA: 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: 10%
At or near the surface: 9%
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 41 of Beaver County's 435 square miles on soluble rock, 40 of them with the rock at or near the surface. With about 165,540 residents (381 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 347 map points about 1.1 miles apart, so a pocket smaller than that can be missed or overstated.

Two things to read before deciding: why gypsum and salt move faster than limestone, and how these percentages are measured.

Counties around Beaver County

The nearest county rated sinkhole country is Washington County, MD, about 153 miles southeast. 2 of the 6 closest counties land in the same band; the ground changes quickly around here.

Hancock County, WV 16 mi southwest · 2% at surface
Lawrence County, PA 21 mi north · 6% at surface
Columbiana County, OH 23 mi west · 0% at surface
Allegheny County, PA 24 mi southeast · 28% at surface
Butler County, PA 28 mi northeast · 35% at surface
Jefferson County, OH 29 mi southwest · 31% at surface

Which formation it is

The largest mapped soluble unit here is the Allegheny Formation (sandstone), Pennsylvanian in age, covering about 9% of the county. Next is the Monongahela Group at under 1%.

The county also lies over the Michigan Basin; Ohio Basin; Appalachian Basin, a deep salt or gypsum basin. Deep beds rarely cause surface collapse on their own, but wells and mining into them have.

Against the rest of Pennsylvania

Beaver County ranks 31 of 67 in Pennsylvania for soluble rock at the surface, and sits above 67% of US counties on that measure.