Sinkhole risk in Meagher County, MT: Pockets of it

Pockets of it

Soluble rock at the surface or under thin cover in part of the county.

On soluble rock: 49%
At or near the surface: 49%
Buried under cover: 0%

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 1,167 of Meagher County's 2,392 square miles on soluble rock, 1,167 of them with the rock at or near the surface. With about 2,065 residents (1 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 601 map points about 2.0 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 the signs to look for and how an inspection works.

Counties around Meagher County

The nearest county rated sinkhole country is Fall River County, SD, about 430 miles southeast. 3 of the 6 closest counties land in the same band; the ground changes quickly around here.

Broadwater County, MT 33 mi southwest · 27% at surface
Judith Basin County, MT 42 mi northeast · 33% at surface
Wheatland County, MT 51 mi east · 6% at surface
Cascade County, MT 54 mi north · 18% at surface
Jefferson County, MT 63 mi southwest · 6% at surface
Sweet Grass County, MT 71 mi southeast · 3% at surface

The rock underneath

The largest mapped soluble unit here is the Mississippian, undifferentiated (carbonate), Mississippian in age, covering about 16% of the county. Next is the Cambrian, undifferentiated at 13%.

2% 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 Crazy Mountains 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 Montana

Meagher County ranks 1 of 56 in Montana for soluble rock at the surface, and sits above 87% of US counties on that measure.