Sinkhole risk in Jefferson County, TN: 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%

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 274 of Jefferson County's 275 square miles on soluble rock, 274 of them with the rock at or near the surface. With about 59,217 residents (215 per square mile), there is effectively nowhere in the county off the soluble rock, town or country. The figures come from 243 map points about 1.1 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 Jefferson County

The closest county with no soluble rock mapped is Haywood County, NC, about 43 miles southeast. 5 of the 6 closest counties land in the same band, so this is a regional pattern rather than a local quirk.

Hamblen County, TN 15 mi northeast · 99% at surface
Grainger County, TN 16 mi north · 79% at surface
Sevier County, TN 19 mi south · 36% at surface
Cocke County, TN 20 mi southeast · 50% at surface
Union County, TN 27 mi northwest · 89% at surface
Knox County, TN 28 mi west · 95% at surface

What Jefferson County is built on

The largest mapped soluble unit here is the Sevier Shale (shale), Ordovician in age, covering about 29% of the county. Next is the Jonesboro Limestone, Newala Formation, Mascot Dolomite, Kingsport Formation, Longview Dolomite, and Chepultepec Dolomite at 17%.

Against the rest of Tennessee

Jefferson County ranks 1 of 95 in Tennessee for soluble rock at the surface, and sits above 99% of US counties on that measure.