Sinkhole risk in McNairy County, TN: 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: 11%
At or near the surface: 11%
Buried under cover: 0%

The next step for one property

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

That works out to roughly 62 of McNairy County's 563 square miles on soluble rock, 62 of them with the rock at or near the surface. With about 26,103 residents (46 per square mile), much of the land is open, and the mapped rock may sit far from where people actually live. The figures come from 344 map points about 1.3 miles apart, so a pocket smaller than that can be missed or overstated.

Two things to read before deciding: how these percentages are measured, and the warning signs that apply anywhere.

Counties around McNairy County

The nearest county rated sinkhole country is Tippah County, MS, about 35 miles southwest, close enough that the same rock may run under the county line. 2 of the 6 closest counties land in the same band; the ground changes quickly around here.

Chester County, TN 17 mi north · 0% at surface
Alcorn County, MS 20 mi south · 41% at surface
Hardin County, TN 21 mi east · 9% at surface
Hardeman County, TN 24 mi west · 5% at surface
Madison County, TN 33 mi northwest · 0% at surface
Henderson County, TN 35 mi north · 0% at surface

Which formation it is

The largest mapped soluble unit here is the Demopolis Formation (clay or mud), Cretaceous in age, covering about 8% of the county. Next is the Coon Creek Formation at 3%.

Against the rest of Tennessee

McNairy County ranks 72 of 95 in Tennessee for soluble rock at the surface, and sits above 68% of US counties on that measure.