Sinkhole risk in Jefferson County, PA: Pockets of it

Pockets of it

Soluble rock at the surface or under thin cover in part of the county.

On soluble rock: 24%
At or near the surface: 24%
Buried under cover: 0%

What this means before you buy

Check the parcel against your state survey sinkhole map, and ask for an inspection if cracks, depressions or sticking doors show up.

That works out to roughly 159 of Jefferson County's 652 square miles on soluble rock, 159 of them with the rock at or near the surface. With about 43,367 residents (66 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 315 map points about 1.4 miles apart, so a pocket smaller than that can be missed or overstated.

Worth reading for this county: why gypsum and salt move faster than limestone, and the signs to look for and how an inspection works.

Counties around Jefferson County

The nearest county rated sinkhole country is Union County, PA, about 103 miles east. 3 of the 6 closest counties land in the same band; the ground changes quickly around here.

Clarion County, PA 22 mi west · 36% at surface
Elk County, PA 27 mi northeast · 0% at surface
Forest County, PA 29 mi northwest · 0% at surface
Clearfield County, PA 29 mi east · under 1% at surface
Armstrong County, PA 33 mi southwest · 37% at surface
Indiana County, PA 34 mi south · 16% at surface

The rock underneath

The largest mapped soluble unit here is the Allegheny Formation (sandstone), Pennsylvanian in age, covering about 24% of the county.

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

Jefferson County ranks 24 of 67 in Pennsylvania for soluble rock at the surface, and sits above 77% of US counties on that measure.