Sinkhole risk in Choctaw 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: 7%
At or near the surface: 5%
Buried under cover: 2%

What to do about a house in Choctaw County

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

That works out to roughly 65 of Choctaw County's 913 square miles on soluble rock, 48 of them with the rock at or near the surface. With about 12,052 residents (13 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 268 map points about 1.8 miles apart, so a pocket smaller than that can be missed or overstated.

Two things to read before deciding: why gypsum and salt move faster than limestone, and how these percentages are measured.

Counties around Choctaw County

The nearest county rated sinkhole country is Noxubee County, MS, about 79 miles north. 2 of the 6 closest counties land in the same band; the ground changes quickly around here.

Clarke County, MS 26 mi west · 14% at surface
Marengo County, AL 32 mi northeast · 33% at surface
Clarke County, AL 33 mi southeast · 15% at surface
Wayne County, MS 35 mi southwest · 17% at surface
Lauderdale County, MS 37 mi northwest · 0% at surface
Washington County, AL 40 mi south · 3% at surface

Which formation it is

The largest mapped soluble unit here is the Jackson Group undifferentiated (sand), Eocene in age, covering about 4% of the county. Next is the Oligocene Series undifferentiated at 2%.

The county also lies over the Gulf Coast salt domes, a deep salt or gypsum basin. Deep beds rarely cause surface collapse on their own, but wells and mining into them have.

Against the rest of Alabama

Choctaw County ranks 43 of 67 in Alabama for soluble rock at the surface, and sits above 63% of US counties on that measure.