Sinkhole risk in Howell County, MO: Sinkhole country

Sinkhole country

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

On soluble rock: 100%
At or near the surface: 100%
Buried under cover: 0%

The next step for one property

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

That works out to roughly 927 of Howell County's 927 square miles on soluble rock, 927 of them with the rock at or near the surface. With about 40,762 residents (44 per square mile), there is effectively nowhere in the county off the soluble rock, town or country. The figures come from 386 map points about 1.5 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 Howell County

The closest county with no soluble rock mapped is Cleburne County, AR, about 82 miles south. 6 of the 6 closest counties land in the same band, so this is a regional pattern rather than a local quirk.

Fulton County, AR 27 mi south · 100% at surface
Oregon County, MO 28 mi east · 100% at surface
Ozark County, MO 33 mi west · 100% at surface
Douglas County, MO 37 mi west · 100% at surface
Texas County, MO 38 mi north · 100% at surface
Shannon County, MO 38 mi northeast · 99% at surface

The rock underneath

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 87% of the county. Next is the Roubidoux Formation at 14%.

Against the rest of Missouri

Howell County ranks 6 of 115 in Missouri for soluble rock at the surface, and sits above 99% of US counties on that measure.