Sinkhole risk in Monroe 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: 6%
At or near the surface: under 1%
Buried under cover: 5%

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 35 of Monroe County's 608 square miles on soluble rock, 4 of them with the rock at or near the surface. With about 166,523 residents (274 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 607 map points about 1.0 miles apart, so a pocket smaller than that can be missed or overstated.

Two things to read before deciding: why the 5% under cover still counts, and how these percentages are measured.

Counties around Monroe County

The nearest county rated sinkhole country is Union County, PA, about 90 miles west. 1 of the 6 closest counties land in the same band; the ground changes quickly around here.

Northampton County, PA 21 mi south · 33% at surface
Warren County, NJ 22 mi southeast · 10% at surface
Carbon County, PA 22 mi southwest · under 1% at surface
Pike County, PA 24 mi northeast · 0% at surface
Lackawanna County, PA 30 mi northwest · 0% at surface
Lehigh County, PA 33 mi southwest · 29% at surface

Which formation it is

The largest mapped soluble unit here is the Buttermilk Falls Limestone through Esopus Formation, undivided (sandstone), Devonian in age, covering about 4% of the county. Next is the Decker Formation through Poxono Island Formation, undivided at 2%.

Against the rest of Pennsylvania

Monroe County ranks 46 of 67 in Pennsylvania for soluble rock at the surface, and sits above 54% of US counties on that measure.