Sinkhole risk in Delaware 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 Delaware County

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

That works out to roughly 392 of Delaware County's 392 square miles on soluble rock. With about 112,951 residents (288 per square mile), there is effectively nowhere in the county off the soluble rock, town or country. The figures come from 396 map points about 1.0 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 Delaware County

The nearest county rated sinkhole country is Monroe County, IN, about 95 miles southwest. 6 of the 6 closest counties land in the same band, so this is a regional pattern rather than a local quirk.

Blackford County, IN 17 mi north · 0% at surface
Madison County, IN 18 mi west · 0% at surface
Henry County, IN 21 mi south · 0% at surface
Randolph County, IN 21 mi east · 0% at surface
Grant County, IN 24 mi northwest · 0% at surface
Jay County, IN 25 mi northeast · 0% at surface

The rock underneath

The largest mapped soluble unit here is the Pleasant Mills Formation (dolostone (dolomite)), Silurian in age, covering about 72% of the county. Next is the Louisville Limestone through Brassfield Limestone at 22%.

Against the rest of Indiana

Delaware County ranks 45 of 92 in Indiana for soluble rock at the surface, and sits above 0% of US counties on that measure.