Sinkhole risk in Cole County, MO: Sinkhole country

Sinkhole country

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

On soluble rock: 95%
At or near the surface: 94%
Buried under cover: 1%

What to do about a house in Cole County

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

That works out to roughly 372 of Cole County's 392 square miles on soluble rock, 366 of them with the rock at or near the surface. With about 77,625 residents (198 per square mile), there is effectively nowhere in the county off the soluble rock, town or country. The figures come from 558 map points about 0.8 miles apart, so a pocket smaller than that can be missed or overstated.

Two things to read before deciding: the signs to look for and how an inspection works, and how these percentages are measured.

Counties around Cole County

The closest county with no soluble rock mapped is Schuyler County, MO, about 136 miles north. 5 of the 6 closest counties land in the same band, so this is a regional pattern rather than a local quirk.

Moniteau County, MO 19 mi northwest · 95% at surface
Miller County, MO 21 mi south · 100% at surface
Osage County, MO 23 mi east · 93% at surface
Callaway County, MO 30 mi northeast · 28% at surface
Maries County, MO 30 mi southeast · 100% at surface
Morgan County, MO 33 mi west · 100% at surface

What Cole 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 70% of the county. Next is the Roubidoux Formation at 17%.

Against the rest of Missouri

Cole County ranks 37 of 115 in Missouri for soluble rock at the surface, and sits above 98% of US counties on that measure.