Sinkhole risk in Jefferson 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: 6%
At or near the surface: 5%
Buried under cover: 1%

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 33 of Jefferson County's 570 square miles on soluble rock, 26 of them with the rock at or near the surface. With about 7,136 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 414 map points about 1.2 miles apart, so a pocket smaller than that can be missed or overstated.

Worth reading for this county: how these percentages are measured, and the warning signs that apply anywhere.

Counties around Jefferson County

The nearest county rated sinkhole country is Dickinson County, KS, about 90 miles south. 4 of the 6 closest counties land in the same band, so this is a regional pattern rather than a local quirk.

Saline County, NE 24 mi north · 0% at surface
Thayer County, NE 24 mi west · 2% at surface
Gage County, NE 25 mi east · 0% at surface
Washington County, KS 28 mi south · 15% at surface
Fillmore County, NE 34 mi northwest · 0% at surface
Republic County, KS 36 mi southwest · 19% at surface

Which formation it is

The largest mapped soluble unit here is the Greenhorn Limestone and Graneros Shale (shale), Late Cretaceous in age, covering about 6% of the county. Next is the Chase Group at under 1%.

Against the rest of Nebraska

Jefferson County ranks 25 of 93 in Nebraska for soluble rock at the surface, and sits above 62% of US counties on that measure.