SinkholeOdds

Sinkhole risk in Pierce County, NE: 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
5%
At or near the surface
0%
Buried under cover
5%

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 28 of Pierce County's 573 square miles on soluble rock. With about 7,334 residents (13 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 391 map points about 1.2 miles apart, so a pocket smaller than that can be missed or overstated.

Read next: why gypsum and salt move faster than limestone, and how these percentages are measured.

Counties around Pierce County

The nearest county rated sinkhole country is Knox County, NE, about 29 miles northwest, close enough that the same rock may run under the county line. 4 of the 6 closest counties land in the same band, so this is a regional pattern rather than a local quirk.

Which formation it is

The largest mapped soluble unit here is the Niobrara Formation (limestone), Late Cretaceous in age, covering about 3% of the county. Next is the Pierre Shale at 2%.

2% of the county sits on gypsum or salt, which dissolves in years rather than millennia. That share matters more than its size suggests.

Against the rest of Nebraska

Pierce County ranks 78 of 93 in Nebraska for soluble rock at the surface, and sits above 0% of US counties on that measure.