Sinkhole risk in Franklin County, IN: Pockets of it

Pockets of it

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

On soluble rock: 56%
At or near the surface: 2%
Buried under cover: 55%

What this means before you buy

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 217 of Franklin County's 384 square miles on soluble rock, 7 of them with the rock at or near the surface. With about 23,136 residents (60 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 346 map points about 1.1 miles apart, so a pocket smaller than that can be missed or overstated.

Counties around Franklin County

The nearest county rated sinkhole country is Kenton County, KY, about 44 miles southeast. 2 of the 6 closest counties land in the same band; the ground changes quickly around here.

Union County, IN 17 mi northeast · 0% at surface
Fayette County, IN 17 mi north · 0% at surface
Dearborn County, IN 19 mi south · 10% at surface
Ripley County, IN 24 mi southwest · 6% at surface
Decatur County, IN 24 mi west · 2% at surface
Rush County, IN 26 mi northwest · 0% at surface

The rock underneath

The largest mapped soluble unit here is the Whitewater Formation (limestone), Ordovician in age, covering about 46% of the county. Next is the Louisville Limestone through Brassfield Limestone at 9%.

Against the rest of Indiana

Franklin County ranks 24 of 92 in Indiana for soluble rock at the surface, and sits above 57% of US counties on that measure.