SinkholeOdds

Sinkhole risk in Dundy County, NE: Pockets of it

Pockets of it

Soluble rock at the surface or under thin cover in part of the county.

On soluble rock
17%
At or near the surface
17%
Buried under cover
0%

What to do about a house in Dundy County

Check the parcel against your state survey sinkhole map, and ask for an inspection if cracks, depressions or sticking doors show up.

That works out to roughly 158 of Dundy County's 920 square miles on soluble rock, 158 of them with the rock at or near the surface. With about 1,581 residents (2 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 406 map points about 1.5 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 the signs to look for and how an inspection works.

Counties around Dundy County

The nearest county rated sinkhole country is Harlan County, NE, about 120 miles east. 3 of the 6 closest counties land in the same band; the ground changes quickly around here.

Which formation it is

The largest mapped soluble unit here is the Pierre Shale (shale), Late Cretaceous in age, covering about 17% of the county. Next is the Ogallala Group or Formation at under 1%.

17% of the county sits on gypsum or salt, which dissolves in years rather than millennia. That share matters more than its size suggests.

The county also lies over the Northern Denver 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 Nebraska

Dundy County ranks 19 of 93 in Nebraska for soluble rock at the surface, and sits above 73% of US counties on that measure.