Sinkhole risk in Carbon County, WY: 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: 4%
At or near the surface: 4%
Buried under cover: 0%

What to do about a house in Carbon County

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

That works out to roughly 340 of Carbon County's 7,898 square miles on soluble rock, 340 of them with the rock at or near the surface. With about 14,250 residents (2 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 349 map points about 4.8 miles apart, so a pocket smaller than that can be missed or overstated.

Counties around Carbon County

The nearest county rated sinkhole country is Fall River County, SD, about 203 miles northeast. 5 of the 6 closest counties land in the same band, so this is a regional pattern rather than a local quirk.

Albany County, WY 63 mi east · 12% at surface
Jackson County, CO 78 mi southeast · 4% at surface
Routt County, CO 84 mi south · under 1% at surface
Natrona County, WY 88 mi north · 8% at surface
Sweetwater County, WY 100 mi west · 3% at surface
Moffat County, CO 101 mi southwest · 8% at surface

The rock underneath

The largest mapped soluble unit here is the Niobrara Formation (limestone), Late Cretaceous in age, covering about 2% of the county. Next is the Chugwater Formation (N, NE), or Chugwater Formation or Group (S) at under 1%.

1% of the county sits on gypsum or salt, which dissolves in years rather than millennia. That share matters more than its size suggests.

Against the rest of Wyoming

Carbon County ranks 16 of 23 in Wyoming for soluble rock at the surface, and sits above 62% of US counties on that measure.