Sinkhole risk in Pope 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: 24%
At or near the surface: 19%
Buried under cover: 5%

What to do about a house in Pope County

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 89 of Pope County's 369 square miles on soluble rock, 71 of them with the rock at or near the surface. With about 3,703 residents (10 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 254 map points about 1.2 miles apart, so a pocket smaller than that can be missed or overstated.

Counties around Pope County

The nearest county rated sinkhole country is Hardin County, IL, about 17 miles northeast, close enough that the same rock may run under the county line. 1 of the 6 closest counties land in the same band; the ground changes quickly around here.

Massac County, IL 17 mi southwest · 7% at surface
Hardin County, IL 17 mi northeast · 61% at surface
Livingston County, KY 17 mi southeast · 54% at surface
Johnson County, IL 19 mi west · 19% at surface
Saline County, IL 23 mi north · under 1% at surface
Crittenden County, KY 24 mi east · 66% at surface

What Pope County is built on

The largest mapped soluble unit here is the Lower Chesterian (Glen Dean - Renault) Series (limestone), Mississippian in age, covering about 22% of the county. Next is the Upper Valmeyeran (Aux Vases, Ste. Genevieve, St. Louis) Series at 2%.

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

Pope County ranks 6 of 102 in Illinois for soluble rock at the surface, and sits above 74% of US counties on that measure.