Sinkhole risk in Shannon County, MO: Sinkhole country

Sinkhole country

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

On soluble rock: 99%
At or near the surface: 99%
Buried under cover: 0%

What this means before you buy

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

That works out to roughly 998 of Shannon County's 1,004 square miles on soluble rock, 998 of them with the rock at or near the surface. With about 7,275 residents (7 per square mile), there is effectively nowhere in the county off the soluble rock, town or country. The figures come from 308 map points about 1.8 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 Shannon County

The closest county with no soluble rock mapped is Clay County, AR, about 76 miles southeast. 6 of the 6 closest counties land in the same band, so this is a regional pattern rather than a local quirk.

Reynolds County, MO 27 mi northeast · 98% at surface
Carter County, MO 28 mi southeast · 100% at surface
Dent County, MO 32 mi north · 100% at surface
Oregon County, MO 32 mi south · 100% at surface
Texas County, MO 33 mi west · 100% at surface
Howell County, MO 38 mi southwest · 100% at surface

What Shannon County is built on

The largest mapped soluble unit here is the Roubidoux Formation (sandstone), Early Ordovician-Ibexian Series in age, covering about 40% of the county. Next is the Gasconade Dolomite at 40%.

Against the rest of Missouri

Shannon County ranks 22 of 115 in Missouri for soluble rock at the surface, and sits above 99% of US counties on that measure.