SinkholeOdds

Sinkhole risk in St. Lawrence 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
38%
At or near the surface
under 1%
Buried under cover
37%

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 1,010 of St. Lawrence County's 2,680 square miles on soluble rock, 21 of them with the rock at or near the surface. With about 106,198 residents (40 per square mile), much of the land is open, and the mapped rock may sit far from where people actually live. The figures come from 257 map points about 3.2 miles apart, so a pocket smaller than that can be missed or overstated.

Worth reading for this county: why the 37% under cover still counts, and how these percentages are measured.

Counties around St. Lawrence County

The nearest county rated sinkhole country is Union County, PA, about 264 miles southwest. 5 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 Beekmantown Group (in part) (dolostone (dolomite)), Lower Ordovician in age, covering about 18% of the county. Next is the Theresa Formation at 9%.

Against the rest of New York

St. Lawrence County ranks 2 of 62 in New York for soluble rock at the surface, and sits above 54% of US counties on that measure.