Sinkhole risk in Montour 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: 68%
At or near the surface: 40%
Buried under cover: 29%

The next step for one property

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 89 of Montour County's 130 square miles on soluble rock, 52 of them with the rock at or near the surface. With about 18,115 residents (139 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 428 map points about 0.6 miles apart, so a pocket smaller than that can be missed or overstated.

Two things to read before deciding: why the 29% under cover still counts, and the signs to look for and how an inspection works.

Counties around Montour County

The nearest county rated sinkhole country is Union County, PA, about 21 miles west, close enough that the same rock may run under the county line. 2 of the 6 closest counties land in the same band; the ground changes quickly around here.

Northumberland County, PA 13 mi south · 26% at surface
Columbia County, PA 14 mi east · 4% at surface
Union County, PA 21 mi west · 53% at surface
Snyder County, PA 28 mi southwest · 38% at surface
Sullivan County, PA 29 mi north · 0% at surface
Lycoming County, PA 30 mi northwest · 6% at surface

The rock underneath

The largest mapped soluble unit here is the Hamilton Group (shale), Devonian in age, covering about 36% of the county. Next is the Onondaga and Old Port Formations, undivided at 11%.

Against the rest of Pennsylvania

Montour County ranks 8 of 67 in Pennsylvania for soluble rock at the surface, and sits above 84% of US counties on that measure.