Sinkhole risk in Appanoose County, IA: No soluble rock mapped

No soluble rock mapped

No soluble bedrock mapped.

On soluble rock: under 1%
At or near the surface: 0%
Buried under cover: under 1%

What to do about a house in Appanoose County

No soluble bedrock is mapped here, so natural sinkholes are unlikely. Collapses from broken pipes or old mines are a separate risk.

That works out to roughly 2 of Appanoose County's 497 square miles on soluble rock. With about 12,106 residents (24 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 408 map points about 1.1 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 how these percentages are measured.

Counties around Appanoose County

The nearest county rated sinkhole country is Cooper County, MO, about 131 miles south. 4 of the 6 closest counties land in the same band, so this is a regional pattern rather than a local quirk.

Monroe County, IA 20 mi north · 0% at surface
Putnam County, MO 20 mi south · 0% at surface
Wayne County, IA 24 mi west · 0% at surface
Davis County, IA 24 mi east · 0% at surface
Schuyler County, MO 27 mi southeast · 0% at surface
Lucas County, IA 31 mi northwest · 0% at surface

Which formation it is

The largest mapped soluble unit here is the Marmaton Group (shale), Middle Pennsylvanian-Des Moines Series in age, covering about under 1% of the county.

The county also lies over the Forest City Basin, 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 Iowa

Appanoose County ranks 16 of 99 in Iowa for soluble rock at the surface, and sits above 0% of US counties on that measure.