Sinkhole risk in Whiteside 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: 92%
At or near the surface: under 1%
Buried under cover: 92%

The next step for one property

Sinkholes are uncommon here; watch for new depressions after heavy rain or leaking pipes.

That works out to roughly 631 of Whiteside County's 684 square miles on soluble rock, 2 of them with the rock at or near the surface. With about 54,657 residents (80 per square mile), there is effectively nowhere in the county off the soluble rock, town or country. The figures come from 374 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 the 92% under cover still counts, and how these percentages are measured.

Counties around Whiteside County

The nearest county rated sinkhole country is Jo Daviess County, IL, about 45 miles north. 3 of the 6 closest counties land in the same band; the ground changes quickly around here.

Carroll County, IL 22 mi north · 11% at surface
Henry County, IL 30 mi south · 0% at surface
Bureau County, IL 31 mi southeast · 0% at surface
Lee County, IL 32 mi east · under 1% at surface
Clinton County, IA 34 mi west · 1% at surface
Ogle County, IL 36 mi northeast · 7% at surface

Which formation it is

The largest mapped soluble unit here is the Silurian (dolostone (dolomite)), Silurian in age, covering about 89% of the county. Next is the Galena-Platteville Groups at 3%.

Against the rest of Illinois

Whiteside County ranks 27 of 102 in Illinois for soluble rock at the surface, and sits above 51% of US counties on that measure.