Sinkhole risk in Madison County, OH: 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: 100%
At or near the surface: 0%
Buried under cover: 100%

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 467 of Madison County's 467 square miles on soluble rock. With about 45,531 residents (98 per square mile), there is effectively nowhere in the county off the soluble rock, town or country. The figures come from 272 map points about 1.3 miles apart, so a pocket smaller than that can be missed or overstated.

Worth reading for this county: why the 100% under cover still counts, and how these percentages are measured.

Counties around Madison County

The nearest county rated sinkhole country is Kenton County, KY, about 90 miles southwest. 5 of the 6 closest counties land in the same band, so this is a regional pattern rather than a local quirk.

Clark County, OH 20 mi west · 0% at surface
Franklin County, OH 21 mi east · 0% at surface
Fayette County, OH 24 mi south · 0% at surface
Pickaway County, OH 25 mi southeast · 0% at surface
Champaign County, OH 25 mi northwest · 0% at surface
Union County, OH 28 mi north · 0% at surface

What Madison County is built on

The largest mapped soluble unit here is the Salina Group (dolostone (dolomite)), Silurian in age, covering about 60% of the county. Next is the Tymochtee and Greenfield Formations, Undivided at 29%.

Against the rest of Ohio

Madison County ranks 51 of 88 in Ohio for soluble rock at the surface, and sits above 0% of US counties on that measure.