Sinkhole risk in Adams County, ID: Not karst, but voids possible

Not karst, but voids possible

No soluble bedrock; some pseudokarst (piping or lava-tube ground).

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

What to do about a house in Adams County

Not true karst, but soil piping or lava tubes can still open voids - mention it to an inspector.

That works out to roughly 7 of Adams County's 1,363 square miles on soluble rock, 7 of them with the rock at or near the surface. With about 4,998 residents (4 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 617 map points about 1.5 miles apart, so a pocket smaller than that can be missed or overstated.

Worth reading for this county: how ground with no limestone still opens up, and how these percentages are measured.

Counties around Adams County

The nearest county rated sinkhole country is Emery County, UT, about 501 miles southeast. None of the 6 closest counties land in the same band, so Adams County stands out from its surroundings.

Washington County, ID 34 mi southwest · 0% at surface
Valley County, ID 41 mi east · 1% at surface
Gem County, ID 56 mi south · 0% at surface
Wallowa County, OR 61 mi northwest · 2% at surface
Baker County, OR 62 mi west · 14% at surface
Payette County, ID 62 mi south · 0% at surface

What Adams County is built on

The largest mapped soluble unit here is the Limestone, slate; Upper Triassic greenschist-facies metamorphic rocks; western Idaho, Blue Mountains island-arc complex; (limestone), Late Triassic in age, covering about under 1% of the county.

Against the rest of Idaho

Adams County ranks 24 of 44 in Idaho for soluble rock at the surface, and sits above 53% of US counties on that measure.