Sinkhole risk in Schuyler 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: 34%
At or near the surface: 0%
Buried under cover: 34%

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 150 of Schuyler County's 437 square miles on soluble rock. With about 6,750 residents (15 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 593 map points about 0.9 miles apart, so a pocket smaller than that can be missed or overstated.

Two things to read before deciding: why gypsum and salt move faster than limestone, and why the 34% under cover still counts.

Counties around Schuyler County

The nearest county rated sinkhole country is Calhoun County, IL, about 69 miles south. 5 of the 6 closest counties land in the same band, so this is a regional pattern rather than a local quirk.

Brown County, IL 15 mi southwest · 0% at surface
McDonough County, IL 21 mi north · under 1% at surface
Cass County, IL 23 mi southeast · 0% at surface
Fulton County, IL 30 mi northeast · 0% at surface
Adams County, IL 33 mi west · under 1% at surface
Hancock County, IL 34 mi northwest · 0% at surface

The rock underneath

The largest mapped soluble unit here is the Middle Valmeyeran (Salem, Warsaw, Borden, Springville; includes thin Mvl and Mk in south and east) Series (limestone), Mississippian in age, covering about 21% of the county. Next is the Upper Valmeyeran (Aux Vases, Ste. Genevieve, St. Louis) Series at 10%.

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

Schuyler County ranks 90 of 102 in Illinois for soluble rock at the surface, and sits above 0% of US counties on that measure.