Sinkhole risk in Allen County, OH: Pockets of it

Pockets of it

Soluble rock at the surface or under thin cover in part of the county.

On soluble rock: 100%
At or near the surface: 0%
Buried under cover: 100%

What to do about a house in Allen County

Check the parcel against your state survey sinkhole map, and ask for an inspection if cracks, depressions or sticking doors show up.

That works out to roughly 403 of Allen County's 403 square miles on soluble rock. With about 100,866 residents (251 per square mile), there is effectively nowhere in the county off the soluble rock, town or country. The figures come from 309 map points about 1.1 miles apart, so a pocket smaller than that can be missed or overstated.

Two things to read before deciding: why the 100% under cover still counts, and the signs to look for and how an inspection works.

Counties around Allen County

The nearest county rated sinkhole country is Monroe County, MI, about 85 miles north. 4 of the 6 closest counties land in the same band, so this is a regional pattern rather than a local quirk.

Auglaize County, OH 16 mi southwest · 1% at surface
Putnam County, OH 18 mi north · 0% at surface
Hardin County, OH 24 mi east · 0% at surface
Van Wert County, OH 26 mi west · 0% at surface
Hancock County, OH 28 mi northeast · 0% at surface
Shelby County, OH 30 mi south · 0% at surface

The rock underneath

The largest mapped soluble unit here is the Salina Group (dolostone (dolomite)), Silurian in age, covering about 66% of the county. Next is the Tymochtee and Greenfield Formations, Undivided at 31%.

Against the rest of Ohio

Allen County ranks 12 of 88 in Ohio for soluble rock at the surface, and sits above 0% of US counties on that measure.