Sinkhole risk in Holt 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: 15%
At or near the surface: 15%
Buried under cover: 0%

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 352 of Holt County's 2,412 square miles on soluble rock, 352 of them with the rock at or near the surface. With about 10,120 residents (4 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 364 map points about 2.6 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 how these percentages are measured.

Counties around Holt County

The nearest county rated sinkhole country is Boyd County, NE, about 30 miles north, close enough that the same rock may run under the county line. 1 of the 6 closest counties land in the same band; the ground changes quickly around here.

Boyd County, NE 30 mi north · 69% at surface
Rock County, NE 33 mi west · 5% at surface
Garfield County, NE 39 mi south · 0% at surface
Wheeler County, NE 39 mi south · 0% at surface
Antelope County, NE 42 mi southeast · 0% at surface
Knox County, NE 47 mi east · 22% at surface

The rock underneath

The largest mapped soluble unit here is the Pierre Shale (shale), Late Cretaceous in age, covering about 15% of the county.

15% 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

Holt County ranks 21 of 93 in Nebraska for soluble rock at the surface, and sits above 71% of US counties on that measure.