SinkholeOdds

Sinkhole risk in Ransom County, ND: 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
24%
At or near the surface
under 1%
Buried under cover
24%

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 210 of Ransom County's 862 square miles on soluble rock, 6 of them with the rock at or near the surface. With about 5,590 residents (6 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 406 map points about 1.5 miles apart, so a pocket smaller than that can be missed or overstated.

Worth reading for this county: why the 24% under cover still counts, and how these percentages are measured.

Counties around Ransom County

The nearest county rated sinkhole country is Boyd County, NE, about 252 miles south. 4 of the 6 closest counties land in the same band, so this is a regional pattern rather than a local quirk.

Which formation it is

The largest mapped soluble unit here is the Niobrara and Carlile Formations, Undivided (limestone), Cretaceous in age, covering about 24% of the county.

Against the rest of North Dakota

Ransom County ranks 2 of 53 in North Dakota for soluble rock at the surface, and sits above 54% of US counties on that measure.