Sinkhole risk in Champaign County, IL: 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: 25%
At or near the surface: 0%
Buried under cover: 25%

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 247 of Champaign County's 996 square miles on soluble rock. With about 212,374 residents (213 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 400 map points about 1.6 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 why the 25% under cover still counts.

Counties around Champaign County

The nearest county rated sinkhole country is Monroe County, IN, about 112 miles southeast. 2 of the 6 closest counties land in the same band; the ground changes quickly around here.

Piatt County, IL 23 mi southwest · 0% at surface
Vermilion County, IL 25 mi east · 0% at surface
Douglas County, IL 26 mi south · 0% at surface
Ford County, IL 32 mi north · 0% at surface
De Witt County, IL 37 mi west · 0% at surface
Edgar County, IL 40 mi southeast · 0% at surface

The rock underneath

The largest mapped soluble unit here is the Middle Devonian (limestone), Devonian in age, covering about 12% of the county. Next is the Kinderhookian Series at 7%.

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 Illinois

Champaign County ranks 33 of 102 in Illinois for soluble rock at the surface, and sits above 0% of US counties on that measure.