Sinkhole risk in Shelby 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%

The next step for one property

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

That works out to roughly 409 of Shelby County's 411 square miles on soluble rock. With about 45,654 residents (111 per square mile), there is effectively nowhere in the county off the soluble rock, town or country. The figures come from 399 map points about 1.0 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 how these percentages are measured.

Counties around Shelby County

The nearest county rated sinkhole country is Monroe County, IN, about 46 miles southwest. 5 of the 6 closest counties land in the same band, so this is a regional pattern rather than a local quirk.

Johnson County, IN 16 mi west · 0% at surface
Rush County, IN 19 mi east · 0% at surface
Hancock County, IN 21 mi north · 0% at surface
Decatur County, IN 22 mi southeast · 2% at surface
Bartholomew County, IN 23 mi south · 0% at surface
Marion County, IN 26 mi northwest · 0% at surface

The rock underneath

The largest mapped soluble unit here is the Muscatatuck Group (limestone), Devonian in age, covering about 88% of the county. Next is the Louisville Limestone through Brassfield Limestone at 6%.

Against the rest of Indiana

Shelby County ranks 78 of 92 in Indiana for soluble rock at the surface, and sits above 0% of US counties on that measure.