Sinkhole risk in Monroe 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: 42%
At or near the surface: 12%
Buried under cover: 30%

What this means before you buy

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

That works out to roughly 430 of Monroe County's 1,026 square miles on soluble rock, 118 of them with the rock at or near the surface. With about 19,057 residents (19 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 487 map points about 1.5 miles apart, so a pocket smaller than that can be missed or overstated.

Worth reading for this county: why gypsum and salt move faster than limestone, and why the 30% under cover still counts.

Counties around Monroe County

The nearest county rated sinkhole country is Geneva County, AL, about 98 miles east. 1 of the 6 closest counties land in the same band; the ground changes quickly around here.

Conecuh County, AL 25 mi southeast · 16% at surface
Clarke County, AL 27 mi west · 15% at surface
Wilcox County, AL 29 mi north · 27% at surface
Escambia County, AL 34 mi south · 0% at surface
Butler County, AL 43 mi east · 25% at surface
Washington County, AL 50 mi west · 3% at surface

What Monroe County is built on

The largest mapped soluble unit here is the Oligocene Series undifferentiated (limestone), Oligocene in age, covering about 30% of the county. Next is the Oligocene Series undifferentiated at 7%.

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

Monroe County ranks 39 of 67 in Alabama for soluble rock at the surface, and sits above 69% of US counties on that measure.