SinkholeOdds

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

What this means before you buy

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 135 of McPherson County's 898 square miles on soluble rock, 135 of them with the rock at or near the surface. With about 30,334 residents (34 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 1.5 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 McPherson County

The nearest county rated sinkhole country is Marion County, KS, about 30 miles east, close enough that the same rock may run under the county line. 3 of the 6 closest counties land in the same band; the ground changes quickly around here.

What McPherson County is built on

The largest mapped soluble unit here is the Sumner Group (shale), Late Permian - Cimarronian in age, covering about 7% of the county. Next is the Ogallala Formation at 5%.

10% 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 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

McPherson County ranks 66 of 105 in Kansas for soluble rock at the surface, and sits above 71% of US counties on that measure.