Sinkhole risk in Alger County, MI: Pockets of it
Pockets of it
Soluble rock at the surface or under thin cover in part of the county.
- On soluble rock
- 73%
- At or near the surface
- 0%
- Buried under cover
- 73%
What this means before you buy
Check the parcel against your state survey sinkhole map, and ask for an inspection if cracks, depressions or sticking doors show up.
That works out to roughly 670 of Alger County's 915 square miles on soluble rock. With about 8,695 residents (10 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 455 map points about 1.4 miles apart, so a pocket smaller than that can be missed or overstated.
Read next: why the 73% under cover still counts, and the signs to look for and how an inspection works.
Counties around Alger County
The nearest county rated sinkhole country is Emmet County, MI, about 103 miles southeast. 4 of the 6 closest counties land in the same band, so this is a regional pattern rather than a local quirk.
- Schoolcraft County, MI 41 mi southeast · 1% at surface
- Marquette County, MI 45 mi west · 0% at surface
- Delta County, MI 51 mi south · 0% at surface
- Luce County, MI 54 mi east · under 1% at surface
- Dickinson County, MI 68 mi southwest · 0% at surface
- Mackinac County, MI 69 mi east · under 1% at surface
What Alger County is built on
The largest mapped soluble unit here is the Prairie du Chien Group (shale), Lower Ordovician in age, covering about 27% of the county. Next is the Trempealeau Formation at 21%.
Against the rest of Michigan
Alger County ranks 13 of 83 in Michigan for soluble rock at the surface, and sits above 0% of US counties on that measure.
- Charlevoix County 11%
- Leelanau County 7%
- Cheboygan County 1%
- Schoolcraft County 1%
- Luce County under 1%