SinkholeOdds

Sinkhole risk in Orleans 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
18%
At or near the surface
0%
Buried under cover
18%

What to do about a house in Orleans County

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

That works out to roughly 71 of Orleans County's 391 square miles on soluble rock. With about 39,686 residents (101 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 392 map points about 1.0 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 18% under cover still counts.

Counties around Orleans County

The nearest county rated sinkhole country is Union County, PA, about 175 miles south. 4 of the 6 closest counties land in the same band, so this is a regional pattern rather than a local quirk.

The rock underneath

The largest mapped soluble unit here is the Camillus, Syracuse, and Vernon Formations (shale), Upper Silurian in age, covering about 9% of the county. Next is the Decew Dolostone and Rochester Shale at 5%.

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

Orleans County ranks 39 of 62 in New York for soluble rock at the surface, and sits above 0% of US counties on that measure.