SinkholeOdds

Sinkhole risk in Hamilton County, TN: Sinkhole country

Sinkhole country

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

On soluble rock
70%
At or near the surface
70%
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 378 of Hamilton County's 542 square miles on soluble rock, 378 of them with the rock at or near the surface. With about 386,256 residents (712 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 598 map points about 1.0 miles apart, so a pocket smaller than that can be missed or overstated.

Two things to read before deciding: the signs to look for and how an inspection works, and how these percentages are measured.

Counties around Hamilton County

The closest county with no soluble rock mapped is Gilmer County, GA, about 53 miles southeast. 3 of the 6 closest counties land in the same band; the ground changes quickly around here.

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 17% of the county. Next is the Chickamauga Group, includes Upper part of Chickamauga Group (Reedsville Shale, and Unnamed limestone unit) and Middle and Lower part of Chickamauga Group (Moccasin Formation, Bays Formation, Ottosee Shale, Holston Formation, Lenoir Limestone, Athens at 13%.

Against the rest of Tennessee

Hamilton County ranks 33 of 95 in Tennessee for soluble rock at the surface, and sits above 93% of US counties on that measure.