SinkholeOdds

Sinkhole risk in Scott County, IL: Pockets of it

Pockets of it

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

On soluble rock
59%
At or near the surface
0%
Buried under cover
59%

The next step for one property

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 147 of Scott County's 251 square miles on soluble rock. With about 4,880 residents (19 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 310 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 59% under cover still counts.

Counties around Scott County

The nearest county rated sinkhole country is Calhoun County, IL, about 34 miles south, close enough that the same rock may run under the county line. None of the 6 closest counties land in the same band, so Scott County stands out from its surroundings.

What Scott County is built on

The largest mapped soluble unit here is the Lower Valmeyeran (Keokuk-Sedalia) Series (limestone), Mississippian in age, covering about 27% of the county. Next is the Middle Valmeyeran (Salem, Warsaw, Borden, Springville; includes thin Mvl and Mk in south and east) Series at 17%.

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

Scott County ranks 91 of 102 in Illinois for soluble rock at the surface, and sits above 0% of US counties on that measure.