Sinkhole risk in Phillips County, MT: No soluble rock mapped

No soluble rock mapped

No soluble bedrock mapped.

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

What this means before you buy

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 21 of Phillips County's 5,140 square miles on soluble rock, 21 of them with the rock at or near the surface. With about 4,214 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 246 map points about 4.6 miles apart, so a pocket smaller than that can be missed or overstated.

Worth reading for this county: how these percentages are measured, and the warning signs that apply anywhere.

Counties around Phillips County

The nearest county rated sinkhole country is Fall River County, SD, about 407 miles southeast. 5 of the 6 closest counties land in the same band, so this is a regional pattern rather than a local quirk.

Blaine County, MT 49 mi west · under 1% at surface
Valley County, MT 58 mi east · 0% at surface
Petroleum County, MT 78 mi south · 0% at surface
Garfield County, MT 81 mi southeast · 0% at surface
Fergus County, MT 93 mi southwest · 12% at surface
Hill County, MT 103 mi west · 0% at surface

What Phillips County is built on

The largest mapped soluble unit here is the Mississippian, undifferentiated (carbonate), Mississippian in age, covering about under 1% of the county.

Against the rest of Montana

Phillips County ranks 34 of 56 in Montana for soluble rock at the surface, and sits above 52% of US counties on that measure.