SinkholeOdds

Sinkhole risk in Martin County, MN: 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
11%
At or near the surface
0%
Buried under cover
11%

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 80 of Martin County's 712 square miles on soluble rock. With about 19,561 residents (27 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 390 map points about 1.4 miles apart, so a pocket smaller than that can be missed or overstated.

Worth reading for this county: why the 11% under cover still counts, and how these percentages are measured.

Counties around Martin County

The nearest county rated sinkhole country is Clayton County, IA, about 172 miles east. 3 of the 6 closest counties land in the same band; the ground changes quickly around here.

Which formation it is

The largest mapped soluble unit here is the Upper Cambrian, undivided (dolostone (dolomite)), Late Cambrian in age, covering about 5% of the county. Next is the Upper and Middle Ordovician rocks, undivided at 4%.

Against the rest of Minnesota

Martin County ranks 50 of 87 in Minnesota for soluble rock at the surface, and sits above 0% of US counties on that measure.