Sinkhole risk in Jackson 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 to do about a house in Jackson County

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

Across 1,864 square miles, under one square mile of Jackson County maps onto soluble rock. With about 2,737 residents (1 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 339 map points about 2.3 miles apart, so a pocket smaller than that can be missed or overstated.

Two things to read before deciding: how ground with no limestone still opens up, and how these percentages are measured.

Counties around Jackson County

The nearest county rated sinkhole country is Fall River County, SD, about 100 miles west. 2 of the 6 closest counties land in the same band; the ground changes quickly around here.

Bennett County, SD 34 mi south · 0% at surface
Haakon County, SD 42 mi north · 0% at surface
Mellette County, SD 44 mi east · 0% at surface
Jones County, SD 51 mi east · 0% at surface
Oglala Lakota County, SD 53 mi southwest · 4% at surface
Todd County, SD 56 mi southeast · 0% at surface

Against the rest of South Dakota

Jackson County ranks 40 of 66 in South Dakota for soluble rock at the surface, and sits above 0% of US counties on that measure.