Sinkhole risk in Davidson County, TN: Sinkhole country

Sinkhole country

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

On soluble rock: 75%
At or near the surface: 75%
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 376 of Davidson County's 504 square miles on soluble rock, 376 of them with the rock at or near the surface. With about 729,505 residents (1,449 per square mile), most of the county is built up, so a mapped unit is likely to sit under somebody's street. The figures come from 582 map points about 0.9 miles apart, so a pocket smaller than that can be missed or overstated.

Counties around Davidson County

The closest county with no soluble rock mapped is Henry County, TN, about 85 miles west. 5 of the 6 closest counties land in the same band, so this is a regional pattern rather than a local quirk.

Cheatham County, TN 19 mi west · 39% at surface
Williamson County, TN 20 mi south · 72% at surface
Robertson County, TN 25 mi north · 92% at surface
Wilson County, TN 28 mi east · 94% at surface
Sumner County, TN 28 mi northeast · 70% at surface
Rutherford County, TN 30 mi southeast · 100% at surface

The rock underneath

The largest mapped soluble unit here is the Nashville Group; Bigby-Cannon Limestone and Hermitage Formation (calcarenite), Ordovician in age, covering about 24% of the county. Next is the Ordovician [units] including Richmond Group (which includes Mannie Shale, Fernvale Limestone, Sequatchie Formation, and Arnheim Formation), the Maysville Group (which includes Leipers Formation), the Eden Group (which includes Inman Formation), and at 24%.

Against the rest of Tennessee

Davidson County ranks 25 of 95 in Tennessee for soluble rock at the surface, and sits above 94% of US counties on that measure.