Sinkhole risk in Roane 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%

What to do about a house in Roane County

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

That works out to roughly 266 of Roane County's 361 square miles on soluble rock, 266 of them with the rock at or near the surface. With about 56,742 residents (157 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 491 map points about 0.9 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 Roane County

The closest county with no soluble rock mapped is Morgan County, TN, about 21 miles north. 3 of the 6 closest counties land in the same band; the ground changes quickly around here.

Loudon County, TN 14 mi southeast · 99% at surface
Morgan County, TN 21 mi north · under 1% at surface
Anderson County, TN 26 mi northeast · 50% at surface
Cumberland County, TN 27 mi west · 3% at surface
Meigs County, TN 28 mi southwest · 91% at surface
Rhea County, TN 29 mi southwest · 47% at surface

Which formation it is

The largest mapped soluble unit here is the Knox Group, including Newala Formation, Mascot Dolomite, Kingsport Formation, Longview Dolomite, Chepultepec Dolomite, and Copper Ridge Dolomite (dolostone (dolomite)), Ordovician to Cambrian in age, covering about 20% of the county. Next is the Nolichucky Shale, and Maryville, Rogersville, and Rutledge Formations, and Pumpkin Valley Shale at 18%.

Against the rest of Tennessee

Roane County ranks 27 of 95 in Tennessee for soluble rock at the surface, and sits above 93% of US counties on that measure.