Sinkhole risk in Etowah County, AL: Pockets of it

Pockets of it

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

On soluble rock: 46%
At or near the surface: 46%
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 245 of Etowah County's 535 square miles on soluble rock, 245 of them with the rock at or near the surface. With about 103,207 residents (193 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 611 map points about 0.9 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 Etowah County

The nearest county rated sinkhole country is Cherokee County, AL, about 22 miles east, close enough that the same rock may run under the county line. 4 of the 6 closest counties land in the same band, so this is a regional pattern rather than a local quirk.

Cherokee County, AL 22 mi east · 57% at surface
Calhoun County, AL 23 mi southeast · 52% at surface
Marshall County, AL 24 mi northwest · 29% at surface
St. Clair County, AL 28 mi southwest · 45% at surface
Blount County, AL 31 mi west · 23% at surface
DeKalb County, AL 31 mi northeast · 21% at surface

The rock underneath

The largest mapped soluble unit here is the Conasauga Formation (limestone), Cambrian in age, covering about 17% of the county. Next is the Knox Group undifferentiated at 8%.

Against the rest of Alabama

Etowah County ranks 14 of 67 in Alabama for soluble rock at the surface, and sits above 86% of US counties on that measure.