Sinkhole risk in Montgomery County, MO: Pockets of it

Pockets of it

Soluble rock at the surface or under thin cover in part of the county.

On soluble rock: 73%
At or near the surface: 30%
Buried under cover: 43%

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 535 square miles on soluble rock, 158 of them with the rock at or near the surface. With about 11,511 residents (22 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 324 map points about 1.3 miles apart, so a pocket smaller than that can be missed or overstated.

Counties around Montgomery County

The nearest county rated sinkhole country is Gasconade County, MO, about 34 miles south, close enough that the same rock may run under the county line. 5 of the 6 closest counties land in the same band, so this is a regional pattern rather than a local quirk.

Warren County, MO 20 mi southeast · 42% at surface
Callaway County, MO 26 mi west · 28% at surface
Audrain County, MO 28 mi northwest · 0% at surface
Lincoln County, MO 28 mi east · 0% at surface
Pike County, MO 32 mi northeast · 0% at surface
Gasconade County, MO 34 mi south · 97% at surface

The rock underneath

The largest mapped soluble unit here is the Osagean Series (limestone), Early Mississippian-Osagean Series in age, covering about 29% of the county. Next is the Marmaton Group at 17%.

Against the rest of Missouri

Montgomery County ranks 63 of 115 in Missouri for soluble rock at the surface, and sits above 79% of US counties on that measure.