Sinkhole risk in Talladega County, AL: Sinkhole country

Sinkhole country

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

On soluble rock: 60%
At or near the surface: 60%
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 442 of Talladega County's 737 square miles on soluble rock, 442 of them with the rock at or near the surface. With about 81,375 residents (110 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 472 map points about 1.2 miles apart, so a pocket smaller than that can be missed or overstated.

Counties around Talladega County

The closest county with no soluble rock mapped is Clay County, AL, about 19 miles east. 1 of the 6 closest counties land in the same band; the ground changes quickly around here.

Clay County, AL 19 mi east · 0% at surface
St. Clair County, AL 25 mi north · 45% at surface
Shelby County, AL 29 mi west · 30% at surface
Coosa County, AL 31 mi south · 3% at surface
Calhoun County, AL 34 mi northeast · 52% at surface
Tallapoosa County, AL 41 mi southeast · 0% at surface

Which formation it is

The largest mapped soluble unit here is the Knox Group undifferentiated in part (dolostone (dolomite)), Ordovician-Cambrian in age, covering about 48% of the county. Next is the Conasauga Formation at 5%.

Against the rest of Alabama

Talladega County ranks 4 of 67 in Alabama for soluble rock at the surface, and sits above 90% of US counties on that measure.