Sinkhole risk in Clay 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: 36%
At or near the surface: 35%
Buried under cover: 1%

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 234 of Clay County's 645 square miles on soluble rock, 228 of them with the rock at or near the surface. With about 7,969 residents (12 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 399 map points about 1.3 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 Clay County

The nearest county rated sinkhole country is Dickinson County, KS, about 33 miles south, close enough that the same rock may run under the county line. 4 of the 6 closest counties land in the same band, so this is a regional pattern rather than a local quirk.

Riley County, KS 24 mi east · 73% at surface
Cloud County, KS 27 mi west · 22% at surface
Ottawa County, KS 30 mi southwest · 4% at surface
Washington County, KS 30 mi north · 15% at surface
Geary County, KS 32 mi southeast · 75% at surface
Dickinson County, KS 33 mi south · 79% at surface

The rock underneath

The largest mapped soluble unit here is the Sumner Group (shale), Late Permian - Cimarronian in age, covering about 22% of the county. Next is the Chase Group at 15%.

22% 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 Kansas

Clay County ranks 42 of 105 in Kansas for soluble rock at the surface, and sits above 82% of US counties on that measure.