Sinkhole risk in Ellis County, KS: Pockets of it

Pockets of it

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

On soluble rock: 39%
At or near the surface: 39%
Buried under cover: 0%

The next step for one property

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 355 of Ellis County's 900 square miles on soluble rock, 355 of them with the rock at or near the surface. With about 29,007 residents (32 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 411 map points about 1.5 miles apart, so a pocket smaller than that can be missed or overstated.

Two things to read before deciding: why gypsum and salt move faster than limestone, and the signs to look for and how an inspection works.

Counties around Ellis County

The nearest county rated sinkhole country is Harlan County, NE, about 87 miles north. 6 of the 6 closest counties land in the same band, so this is a regional pattern rather than a local quirk.

Rush County, KS 27 mi south · 55% at surface
Russell County, KS 29 mi east · 47% at surface
Trego County, KS 29 mi west · 57% at surface
Rooks County, KS 30 mi north · 48% at surface
Osborne County, KS 42 mi northeast · 39% at surface
Barton County, KS 42 mi southeast · 37% at surface

What Ellis County is built on

The largest mapped soluble unit here is the Niobrara Chalk (shale), Late Cretaceous in age, covering about 18% of the county. Next is the Carlile Shale at 15%.

The county also lies over the Permian Basin, Anadarko Basin,Dalhart Basin, Palo Duro 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 Kansas

Ellis County ranks 34 of 105 in Kansas for soluble rock at the surface, and sits above 84% of US counties on that measure.