Sinkhole risk in Blackford County, IN: 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 to do about a house in Blackford County

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

That works out to roughly 165 of Blackford County's 165 square miles on soluble rock. With about 11,816 residents (72 per square mile), there is effectively nowhere in the county off the soluble rock, town or country. The figures come from 381 map points about 0.7 miles apart, so a pocket smaller than that can be missed or overstated.

Counties around Blackford County

The nearest county rated sinkhole country is Monroe County, IN, about 111 miles southwest. 6 of the 6 closest counties land in the same band, so this is a regional pattern rather than a local quirk.

Jay County, IN 17 mi east · 0% at surface
Delaware County, IN 17 mi south · 0% at surface
Grant County, IN 18 mi west · 0% at surface
Wells County, IN 19 mi north · under 1% at surface
Huntington County, IN 26 mi north · under 1% at surface
Randolph County, IN 27 mi southeast · 0% at surface

What Blackford County is built on

The largest mapped soluble unit here is the Pleasant Mills Formation (dolostone (dolomite)), Silurian in age, covering about 40% of the county. Next is the Louisville Limestone through Brassfield Limestone at 37%.

Against the rest of Indiana

Blackford County ranks 38 of 92 in Indiana for soluble rock at the surface, and sits above 0% of US counties on that measure.