Sinkhole risk in Kankakee 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: 88%
At or near the surface: 6%
Buried under cover: 82%

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 595 of Kankakee County's 676 square miles on soluble rock, 40 of them with the rock at or near the surface. With about 106,410 residents (157 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 355 map points about 1.4 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 82% under cover still counts.

Counties around Kankakee County

The nearest county rated sinkhole country is Jo Daviess County, IL, about 148 miles northwest. 1 of the 6 closest counties land in the same band; the ground changes quickly around here.

Will County, IL 22 mi north · 3% at surface
Newton County, IN 27 mi southeast · 0% at surface
Iroquois County, IL 27 mi south · 0% at surface
Grundy County, IL 30 mi west · 0% at surface
Lake County, IN 34 mi northeast · 0% at surface
Jasper County, IN 40 mi east · 0% at surface

What Kankakee County is built on

The largest mapped soluble unit here is the Silurian (dolostone (dolomite)), Silurian in age, covering about 88% of the county.

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

Kankakee County ranks 14 of 102 in Illinois for soluble rock at the surface, and sits above 64% of US counties on that measure.