Sinkhole risk in Lewis County, MO: Mostly deep or small

Mostly deep or small

Some soluble rock, mostly deeply buried or in a small share of the county.

On soluble rock: 94%
At or near the surface: 0%
Buried under cover: 94%

What this means before you buy

Sinkholes are uncommon here; watch for new depressions after heavy rain or leaking pipes.

That works out to roughly 474 of Lewis County's 505 square miles on soluble rock. With about 9,852 residents (20 per square mile), there is effectively nowhere in the county off the soluble rock, town or country. The figures come from 347 map points about 1.2 miles apart, so a pocket smaller than that can be missed or overstated.

Two things to read before deciding: why the 94% under cover still counts, and how these percentages are measured.

Counties around Lewis County

The nearest county rated sinkhole country is Calhoun County, IL, about 85 miles southeast. 5 of the 6 closest counties land in the same band, so this is a regional pattern rather than a local quirk.

Marion County, MO 20 mi south · 0% at surface
Clark County, MO 22 mi north · 0% at surface
Knox County, MO 22 mi west · 0% at surface
Shelby County, MO 28 mi southwest · 0% at surface
Adams County, IL 29 mi east · under 1% at surface
Scotland County, MO 33 mi northwest · 0% at surface

What Lewis County is built on

The largest mapped soluble unit here is the Meramecian Series (limestone), Late Mississippian-Meramecian Series in age, covering about 61% of the county. Next is the Osagean Series at 33%.

Against the rest of Missouri

Lewis County ranks 95 of 115 in Missouri for soluble rock at the surface, and sits above 0% of US counties on that measure.