Sinkhole risk in Marshall 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: 29%
At or near the surface: 29%
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 165 of Marshall County's 566 square miles on soluble rock, 165 of them with the rock at or near the surface. With about 102,156 residents (181 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 243 map points about 1.5 miles apart, so a pocket smaller than that can be missed or overstated.

Counties around Marshall County

The nearest county rated sinkhole country is Morgan County, AL, about 32 miles west, close enough that the same rock may run under the county line. 3 of the 6 closest counties land in the same band; the ground changes quickly around here.

Etowah County, AL 24 mi southeast · 46% at surface
Blount County, AL 27 mi southwest · 23% at surface
DeKalb County, AL 31 mi east · 21% at surface
Morgan County, AL 32 mi west · 56% at surface
Cullman County, AL 34 mi west · 0% at surface
Madison County, AL 34 mi northwest · 59% at surface

The rock underneath

The largest mapped soluble unit here is the Bangor Limestone (limestone), Mississippian in age, covering about 14% of the county. Next is the Pennington Formation at 6%.

Against the rest of Alabama

Marshall County ranks 24 of 67 in Alabama for soluble rock at the surface, and sits above 79% of US counties on that measure.