Sinkhole risk in Pettis County, MO: Sinkhole country

Sinkhole country

Soluble rock at or near the surface across much of the county.

On soluble rock: 72%
At or near the surface: 71%
Buried under cover: under 1%

What to do about a house in Pettis County

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

That works out to roughly 488 of Pettis County's 682 square miles on soluble rock, 486 of them with the rock at or near the surface. With about 43,791 residents (64 per square mile), homes are spread across towns and farmland, and a mapped unit may or may not reach the developed parts. The figures come from 363 map points about 1.4 miles apart, so a pocket smaller than that can be missed or overstated.

Worth reading for this county: the signs to look for and how an inspection works, and how these percentages are measured.

Counties around Pettis County

The closest county with no soluble rock mapped is Putnam County, MO, about 122 miles north. 4 of the 6 closest counties land in the same band, so this is a regional pattern rather than a local quirk.

Cooper County, MO 27 mi east · 83% at surface
Johnson County, MO 28 mi west · 50% at surface
Saline County, MO 29 mi north · 10% at surface
Benton County, MO 29 mi south · 89% at surface
Morgan County, MO 31 mi southeast · 100% at surface
Henry County, MO 36 mi southwest · 18% at surface

What Pettis County is built on

The largest mapped soluble unit here is the Smithville Dolomite, Powell Dolomite, Cotter Dolomite, Jefferson City Dolomite (dolostone (dolomite)), Early Ordovician-Ibexian Series in age, covering about 31% of the county. Next is the Kinderhookian Series at 21%.

Against the rest of Missouri

Pettis County ranks 51 of 115 in Missouri for soluble rock at the surface, and sits above 93% of US counties on that measure.