Sinkhole risk in Bureau 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: 36%
At or near the surface: 0%
Buried under cover: 36%

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 314 of Bureau County's 869 square miles on soluble rock. With about 32,486 residents (37 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 324 map points about 1.6 miles apart, so a pocket smaller than that can be missed or overstated.

Worth reading for this county: why gypsum and salt move faster than limestone, and why the 36% under cover still counts.

Counties around Bureau County

The nearest county rated sinkhole country is Jo Daviess County, IL, about 75 miles northwest. 3 of the 6 closest counties land in the same band; the ground changes quickly around here.

Putnam County, IL 18 mi southeast · 0% at surface
Stark County, IL 25 mi southwest · 0% at surface
Lee County, IL 27 mi northeast · under 1% at surface
Marshall County, IL 27 mi south · 0% at surface
Whiteside County, IL 31 mi northwest · under 1% at surface
Henry County, IL 31 mi west · 0% at surface

The rock underneath

The largest mapped soluble unit here is the Silurian (dolostone (dolomite)), Silurian in age, covering about 35% of the county. Next is the Galena-Platteville Groups at under 1%.

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

Bureau County ranks 31 of 102 in Illinois for soluble rock at the surface, and sits above 0% of US counties on that measure.