SinkholeOdds

Sinkhole risk in Williamson County, TN: Sinkhole country

Sinkhole country

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

On soluble rock
72%
At or near the surface
72%
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 417 of Williamson County's 583 square miles on soluble rock, 417 of them with the rock at or near the surface. With about 269,136 residents (462 per square mile), homes are spread across towns and farmland, and a mapped unit may or may not reach the developed parts. The figures come from 288 map points about 1.4 miles apart, so a pocket smaller than that can be missed or overstated.

Worth reading for this county: the signs to look for and how an inspection works, and how these percentages are measured.

Counties around Williamson County

The closest county with no soluble rock mapped is Henry County, TN, about 84 miles west. 5 of the 6 closest counties land in the same band, so this is a regional pattern rather than a local quirk.

What Williamson County is built on

The largest mapped soluble unit here is the Nashville Group; Bigby-Cannon Limestone and Hermitage Formation (calcarenite), Ordovician in age, covering about 38% 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 14%.

Against the rest of Tennessee

Williamson County ranks 30 of 95 in Tennessee for soluble rock at the surface, and sits above 93% of US counties on that measure.