Sinkhole risk in Hardin 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: 9%
At or near the surface: 9%
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 53 of Hardin County's 577 square miles on soluble rock, 53 of them with the rock at or near the surface. With about 27,617 residents (48 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 353 map points about 1.3 miles apart, so a pocket smaller than that can be missed or overstated.

Worth reading for this county: how these percentages are measured, and the warning signs that apply anywhere.

Counties around Hardin County

The nearest county rated sinkhole country is Colbert County, AL, about 41 miles southeast. 3 of the 6 closest counties land in the same band; the ground changes quickly around here.

Wayne County, TN 21 mi east · 15% at surface
McNairy County, TN 21 mi west · 11% at surface
Decatur County, TN 28 mi north · 32% at surface
Chester County, TN 28 mi northwest · 0% at surface
Alcorn County, MS 31 mi southwest · 41% at surface
Tishomingo County, MS 32 mi south · 10% at surface

The rock underneath

The largest mapped soluble unit here is the Silurian Formations, including Decatur Limestone, Brownsport Group (Lobelville Formation, Bob Limestone, Beech River Formation), Wayne Group (Dixon Formation, Lego Formation, Waldron Shale, Laurel Limestone, Osgood Formation) and Brassfield Limestone (limestone), Silurian in age, covering about 7% of the county. Next is the Devonian Formations, includes Pegram Formation, Camden Formation, Harriman Formation, Flat Gap Limestone, and Ross Formation at 1%.

Against the rest of Tennessee

Hardin County ranks 75 of 95 in Tennessee for soluble rock at the surface, and sits above 67% of US counties on that measure.