SinkholeOdds

Sinkhole risk in Lenawee County, MI: 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
10%
At or near the surface
0%
Buried under cover
10%

What to do about a house in Lenawee County

Sinkholes are uncommon here; watch for new depressions after heavy rain or leaking pipes.

That works out to roughly 73 of Lenawee County's 750 square miles on soluble rock. With about 97,746 residents (130 per square mile), homes are spread across towns and farmland, and a mapped unit may or may not reach the developed parts. The figures come from 379 map points about 1.4 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 why the 10% under cover still counts.

Counties around Lenawee County

The nearest county rated sinkhole country is Monroe County, MI, about 30 miles east, close enough that the same rock may run under the county line. 3 of the 6 closest counties land in the same band; the ground changes quickly around here.

The rock underneath

The largest mapped soluble unit here is the Traverse Group (limestone), Middle Devonian in age, covering about 5% of the county. Next is the Bedford Shale at 4%.

The county also lies over the Michigan Basin; Ohio Basin; Appalachian Basin, a deep salt or gypsum basin. Deep beds rarely cause surface collapse on their own, but wells and mining into them have.

Against the rest of Michigan

Lenawee County ranks 53 of 83 in Michigan for soluble rock at the surface, and sits above 0% of US counties on that measure.