SinkholeOdds

Sinkhole risk in Allegan County, MI: No soluble rock mapped

No soluble rock mapped

No soluble bedrock mapped.

On soluble rock
under 1%
At or near the surface
0%
Buried under cover
under 1%

What to do about a house in Allegan County

No soluble bedrock is mapped here, so natural sinkholes are unlikely. Collapses from broken pipes or old mines are a separate risk.

That works out to roughly 2 of Allegan County's 825 square miles on soluble rock. With about 122,429 residents (148 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 383 map points about 1.5 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 how these percentages are measured.

Counties around Allegan County

The nearest county rated sinkhole country is Barry County, MI, about 50 miles east. 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 Michigan Formation (black shale), Mississippian in age, covering about under 1% of the county.

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

Allegan County ranks 14 of 83 in Michigan for soluble rock at the surface, and sits above 0% of US counties on that measure.