SinkholeOdds

Sinkhole risk in Madison County, NY: 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
20%
At or near the surface
0%
Buried under cover
20%

What to do about a house in Madison County

Sinkholes are uncommon here; watch for new depressions after heavy rain or leaking pipes.

That works out to roughly 128 of Madison County's 655 square miles on soluble rock. With about 67,072 residents (102 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 566 map points about 1.1 miles apart, so a pocket smaller than that can be missed or overstated.

Read next: why gypsum and salt move faster than limestone, and why the 20% under cover still counts.

Counties around Madison County

The nearest county rated sinkhole country is Union County, PA, about 152 miles southwest. 5 of the 6 closest counties land in the same band, so this is a regional pattern rather than a local quirk.

What Madison County is built on

The largest mapped soluble unit here is the Vernon Formation (shale), Upper Silurian in age, covering about 7% of the county. Next is the Helderberg Group at 6%.

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 New York

Madison County ranks 30 of 62 in New York for soluble rock at the surface, and sits above 0% of US counties on that measure.