Sinkhole risk in Carroll 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: 81%
At or near the surface: under 1%
Buried under cover: 81%

What this means before you buy

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

That works out to roughly 302 of Carroll County's 372 square miles on soluble rock, 1 of them with the rock at or near the surface. With about 20,747 residents (56 per square mile), much of the land is open, and the mapped rock may sit far from where people actually live. The figures come from 337 map points about 1.1 miles apart, so a pocket smaller than that can be missed or overstated.

Worth reading for this county: why the 81% under cover still counts, and how these percentages are measured.

Counties around Carroll County

The nearest county rated sinkhole country is Monroe County, IN, about 98 miles south. 6 of the 6 closest counties land in the same band, so this is a regional pattern rather than a local quirk.

Cass County, IN 16 mi northeast · 4% at surface
White County, IN 19 mi northwest · 0% at surface
Clinton County, IN 20 mi south · 0% at surface
Tippecanoe County, IN 22 mi southwest · 0% at surface
Howard County, IN 25 mi east · 0% at surface
Miami County, IN 30 mi northeast · under 1% at surface

Which formation it is

The largest mapped soluble unit here is the Wabash Formation (limestone), Silurian in age, covering about 63% of the county. Next is the Muscatatuck Group at 18%.

Against the rest of Indiana

Carroll County ranks 29 of 92 in Indiana for soluble rock at the surface, and sits above 51% of US counties on that measure.