SinkholeOdds

Sinkhole risk in Oscoda 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
14%
At or near the surface
0%
Buried under cover
14%

The next step for one property

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

That works out to roughly 80 of Oscoda County's 566 square miles on soluble rock. With about 8,596 residents (15 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 403 map points about 1.2 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 14% under cover still counts.

Counties around Oscoda County

The nearest county rated sinkhole country is Crawford County, MI, about 24 miles west, 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.

Which formation it is

The largest mapped soluble unit here is the Michigan Formation (black shale), Mississippian in age, covering about 14% of the county. Next is the Bedford Shale at under 1%.

14% of the county sits on gypsum or salt, which dissolves in years rather than millennia. That share matters more than its size suggests.

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

Oscoda County ranks 71 of 83 in Michigan for soluble rock at the surface, and sits above 0% of US counties on that measure.