Sinkhole risk in Franklin 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: 31%
At or near the surface: 31%
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 198 of Franklin County's 634 square miles on soluble rock, 198 of them with the rock at or near the surface. With about 31,874 residents (50 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 368 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 Franklin County

The nearest county rated sinkhole country is Colbert County, AL, about 18 miles north, close enough that the same rock may run under the county line. None of the 6 closest counties land in the same band, so Franklin County stands out from its surroundings.

Colbert County, AL 18 mi north · 60% at surface
Marion County, AL 21 mi south · 0% at surface
Lawrence County, AL 30 mi east · 60% at surface
Tishomingo County, MS 30 mi northwest · 10% at surface
Itawamba County, MS 32 mi west · 4% at surface
Winston County, AL 34 mi southeast · 0% at surface

The rock underneath

The largest mapped soluble unit here is the Bangor Limestone (limestone), Mississippian in age, covering about 31% of the county.

Against the rest of Alabama

Franklin County ranks 19 of 67 in Alabama for soluble rock at the surface, and sits above 80% of US counties on that measure.