Sinkhole risk in Coffee County, TN: Sinkhole country

Sinkhole country

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

On soluble rock: 74%
At or near the surface: 74%
Buried under cover: 0%

The next step for one property

Get a sinkhole or geotechnical inspection before buying, building or adding weight to a foundation.

That works out to roughly 317 of Coffee County's 429 square miles on soluble rock, 317 of them with the rock at or near the surface. With about 61,285 residents (143 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 267 map points about 1.3 miles apart, so a pocket smaller than that can be missed or overstated.

Counties around Coffee County

The closest county with no soluble rock mapped is Morgan County, TN, about 92 miles northeast. 5 of the 6 closest counties land in the same band, so this is a regional pattern rather than a local quirk.

Moore County, TN 21 mi southwest · 65% at surface
Warren County, TN 21 mi northeast · 81% at surface
Bedford County, TN 21 mi west · 93% at surface
Grundy County, TN 22 mi east · 21% at surface
Cannon County, TN 22 mi north · 63% at surface
Franklin County, TN 23 mi south · 66% at surface

Which formation it is

The largest mapped soluble unit here is the St. Louis Limestone and Warsaw Limestone (limestone), Mississippian in age, covering about 59% 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 9%.

Against the rest of Tennessee

Coffee County ranks 26 of 95 in Tennessee for soluble rock at the surface, and sits above 93% of US counties on that measure.