Sinkhole risk in Coosa County, AL: Mostly deep or small

Mostly deep or small

Some soluble rock, mostly deeply buried or in a small share of the county.

On soluble rock: 3%
At or near the surface: 3%
Buried under cover: 0%

What to do about a house in Coosa County

Sinkholes are uncommon here; watch for new depressions after heavy rain or leaking pipes.

That works out to roughly 18 of Coosa County's 651 square miles on soluble rock, 18 of them with the rock at or near the surface. With about 10,291 residents (16 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 376 map points about 1.3 miles apart, so a pocket smaller than that can be missed or overstated.

Two things to read before deciding: how these percentages are measured, and the warning signs that apply anywhere.

Counties around Coosa County

The nearest county rated sinkhole country is Talladega County, AL, about 31 miles north, close enough that the same rock may run under the county line. 1 of the 6 closest counties land in the same band; the ground changes quickly around here.

Elmore County, AL 24 mi south · 0% at surface
Tallapoosa County, AL 26 mi east · 0% at surface
Chilton County, AL 29 mi west · 6% at surface
Talladega County, AL 31 mi north · 60% at surface
Clay County, AL 32 mi northeast · 0% at surface
Shelby County, AL 33 mi northwest · 30% at surface

What Coosa County is built on

The largest mapped soluble unit here is the Talladega Group; Lay Dam Formation, unnamed diamictite facies (conglomerate), Silurian?-Devonian in age, covering about 1% of the county. Next is the Newala Limestone at under 1%.

Against the rest of Alabama

Coosa County ranks 47 of 67 in Alabama for soluble rock at the surface, and sits above 59% of US counties on that measure.