Sinkhole risk in Harding County, SD: Not karst, but voids possible

Not karst, but voids possible

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

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

What this means before you buy

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

Across 2,672 square miles, under one square mile of Harding County maps onto soluble rock. With about 1,325 residents (0 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 386 map points about 2.6 miles apart, so a pocket smaller than that can be missed or overstated.

Two things to read before deciding: why gypsum and salt move faster than limestone, and how ground with no limestone still opens up.

Counties around Harding County

The nearest county rated sinkhole country is Fall River County, SD, about 164 miles south. 1 of the 6 closest counties land in the same band; the ground changes quickly around here.

Bowman County, ND 36 mi north · 0% at surface
Butte County, SD 48 mi south · 6% at surface
Perkins County, SD 49 mi east · 0% at surface
Carter County, MT 51 mi west · 4% at surface
Adams County, ND 57 mi northeast · 0% at surface
Slope County, ND 59 mi north · under 1% at surface

Against the rest of South Dakota

Harding County ranks 36 of 66 in South Dakota for soluble rock at the surface, and sits above 0% of US counties on that measure.