Sinkhole risk in McMinn County, TN: Sinkhole country

Sinkhole country

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

On soluble rock: 86%
At or near the surface: 86%
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 368 of McMinn County's 430 square miles on soluble rock, 368 of them with the rock at or near the surface. With about 56,754 residents (132 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 241 map points about 1.3 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 McMinn County

The closest county with no soluble rock mapped is Fannin County, GA, about 42 miles southeast. 3 of the 6 closest counties land in the same band; the ground changes quickly around here.

Meigs County, TN 13 mi northwest · 91% at surface
Monroe County, TN 21 mi east · 37% at surface
Rhea County, TN 22 mi northwest · 47% at surface
Polk County, TN 22 mi south · 20% at surface
Bradley County, TN 23 mi southwest · 89% at surface
Loudon County, TN 27 mi northeast · 99% at surface

Which formation it is

The largest mapped soluble unit here is the Nolichucky Shale, and Maryville, Rogersville, and Rutledge Formations, and Pumpkin Valley Shale (shale), Cambrian in age, covering about 23% of the county. Next is the Unnamed (upper part of Knox Group), including Newala Formation, Mascot Dolomite, Kingsport Formation, Longview Dolomite, and Chepultepec Dolomite at 21%.

Against the rest of Tennessee

McMinn County ranks 18 of 95 in Tennessee for soluble rock at the surface, and sits above 96% of US counties on that measure.