Sinkhole risk in Clay County, IA: 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: 2%
At or near the surface: 0%
Buried under cover: 2%

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 10 of Clay County's 567 square miles on soluble rock. With about 16,474 residents (29 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 391 map points about 1.2 miles apart, so a pocket smaller than that can be missed or overstated.

Worth reading for this county: how these percentages are measured, and the warning signs that apply anywhere.

Counties around Clay County

The nearest county rated sinkhole country is Knox County, NE, about 142 miles west. None of the 6 closest counties land in the same band, so Clay County stands out from its surroundings.

Dickinson County, IA 21 mi north · 0% at surface
Buena Vista County, IA 23 mi south · 0% at surface
O'Brien County, IA 24 mi west · 0% at surface
Palo Alto County, IA 24 mi east · 0% at surface
Emmet County, IA 32 mi northeast · 0% at surface
Osceola County, IA 32 mi northwest · 0% at surface

Which formation it is

The largest mapped soluble unit here is the Galena-Decorah-Platteville Formations (dolostone (dolomite)), Middle Ordovician-Mohawkian Series in age, covering about 2% of the county.

Against the rest of Iowa

Clay County ranks 33 of 99 in Iowa for soluble rock at the surface, and sits above 0% of US counties on that measure.