Sinkhole risk in Jackson 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: 5%
At or near the surface: 2%
Buried under cover: 3%

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 25 of Jackson County's 510 square miles on soluble rock, 12 of them with the rock at or near the surface. With about 47,420 residents (93 per square mile), homes are spread across towns and farmland, and a mapped unit may or may not reach the developed parts. The figures come from 302 map points about 1.3 miles apart, so a pocket smaller than that can be missed or overstated.

Worth reading for this county: why gypsum and salt move faster than limestone, and how these percentages are measured.

Counties around Jackson County

The nearest county rated sinkhole country is Washington County, IN, about 22 miles south, close enough that the same rock may run under the county line. 3 of the 6 closest counties land in the same band; the ground changes quickly around here.

Bartholomew County, IN 22 mi north · 0% at surface
Washington County, IN 22 mi south · 62% at surface
Brown County, IN 22 mi northwest · 0% at surface
Scott County, IN 22 mi southeast · 2% at surface
Jennings County, IN 23 mi east · 7% at surface
Lawrence County, IN 24 mi west · 71% at surface

The rock underneath

The largest mapped soluble unit here is the Sanders Group (limestone), Mississippian in age, covering about 4% of the county. Next is the Muscatatuck Group at 1%.

The county also lies over the Illinois Basin, a deep salt or gypsum basin. Deep beds rarely cause surface collapse on their own, but wells and mining into them have.

Against the rest of Indiana

Jackson County ranks 22 of 92 in Indiana for soluble rock at the surface, and sits above 58% of US counties on that measure.