Sinkhole risk in Montgomery 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: 49%
At or near the surface: 49%
Buried under cover: 0%

The next step for one property

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 388 of Montgomery County's 785 square miles on soluble rock, 388 of them with the rock at or near the surface. With about 225,894 residents (288 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 265 map points about 1.7 miles apart, so a pocket smaller than that can be missed or overstated.

Counties around Montgomery County

The nearest county rated sinkhole country is Geneva County, AL, about 80 miles south. 4 of the 6 closest counties land in the same band, so this is a regional pattern rather than a local quirk.

Lowndes County, AL 26 mi west · 49% at surface
Elmore County, AL 27 mi north · 0% at surface
Bullock County, AL 29 mi east · 31% at surface
Pike County, AL 32 mi southeast · 31% at surface
Macon County, AL 32 mi northeast · 8% at surface
Crenshaw County, AL 33 mi south · 30% at surface

Which formation it is

The largest mapped soluble unit here is the Selma Group; Mooreville Chalk (carbonate), Cretaceous in age, covering about 33% of the county. Next is the Selma Group; Demopolis Chalk at 16%.

Against the rest of Alabama

Montgomery County ranks 12 of 67 in Alabama for soluble rock at the surface, and sits above 87% of US counties on that measure.