SinkholeOdds

Sinkhole risk in Ontario 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
26%
At or near the surface
0%
Buried under cover
26%

What to do about a house in Ontario County

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

That works out to roughly 166 of Ontario County's 644 square miles on soluble rock. With about 113,012 residents (175 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 256 map points about 1.6 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 why the 26% under cover still counts.

Counties around Ontario County

The nearest county rated sinkhole country is Union County, PA, about 131 miles south. 3 of the 6 closest counties land in the same band; the ground changes quickly around here.

Which formation it is

The largest mapped soluble unit here is the Akron Dolostone (dolostone (dolomite)), Upper Silurian in age, covering about 11% of the county. Next is the Camillus and Syracuse Formations at 8%.

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

Ontario County ranks 37 of 62 in New York for soluble rock at the surface, and sits above 0% of US counties on that measure.