Sinkhole risk in Marion County, TN: Pockets of it

Pockets of it

Soluble rock at the surface or under thin cover in part of the county.

On soluble rock: 39%
At or near the surface: 39%
Buried under cover: 0%

What this means before you buy

Check the parcel against your state survey sinkhole map, and ask for an inspection if cracks, depressions or sticking doors show up.

That works out to roughly 193 of Marion County's 498 square miles on soluble rock, 193 of them with the rock at or near the surface. With about 29,826 residents (60 per square mile), much of the land is open, and the mapped rock may sit far from where people actually live. The figures come from 313 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 Marion County

The nearest county rated sinkhole country is Hamilton County, TN, about 24 miles east, close enough that the same rock may run under the county line. 3 of the 6 closest counties land in the same band; the ground changes quickly around here.

Grundy County, TN 19 mi north · 21% at surface
Sequatchie County, TN 20 mi northeast · 21% at surface
Dade County, GA 20 mi south · 39% at surface
Hamilton County, TN 24 mi east · 70% at surface
Franklin County, TN 27 mi west · 66% at surface
Catoosa County, GA 32 mi southeast · 63% at surface

The rock underneath

The largest mapped soluble unit here is the Bangor Limestone and Hartselle Formation (limestone), Mississippian in age, covering about 16% of the county. Next is the Monteagle Limestone at 8%.

Against the rest of Tennessee

Marion County ranks 53 of 95 in Tennessee for soluble rock at the surface, and sits above 83% of US counties on that measure.