Sinkhole risk in Dickinson County, KS: Sinkhole country

Sinkhole country

Fast-dissolving gypsum or salt beds under a large part of the county.

On soluble rock: 79%
At or near the surface: 79%
Buried under cover: 0%

What to do about a house in Dickinson County

Get a sinkhole or geotechnical inspection before buying, building or adding weight to a foundation.

That works out to roughly 665 of Dickinson County's 847 square miles on soluble rock, 665 of them with the rock at or near the surface. With about 18,621 residents (22 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 368 map points about 1.5 miles apart, so a pocket smaller than that can be missed or overstated.

Counties around Dickinson County

The closest county with no soluble rock mapped is Stafford County, KS, about 102 miles southwest. 1 of the 6 closest counties land in the same band; the ground changes quickly around here.

Geary County, KS 23 mi northeast · 75% at surface
Saline County, KS 27 mi west · 15% at surface
Morris County, KS 30 mi southeast · 91% at surface
Ottawa County, KS 33 mi northwest · 4% at surface
Clay County, KS 33 mi north · 35% at surface
Marion County, KS 35 mi south · 80% at surface

Which formation it is

The largest mapped soluble unit here is the Sumner Group (shale), Late Permian - Cimarronian in age, covering about 55% of the county. Next is the Chase Group at 23%.

55% 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

Dickinson County ranks 7 of 105 in Kansas for soluble rock at the surface, and sits above 94% of US counties on that measure.