Sinkhole risk in Mesa County, CO: Not karst, but voids possible

Not karst, but voids possible

No soluble bedrock; some pseudokarst (piping or lava-tube ground).

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

What this means before you buy

Not true karst, but soil piping or lava tubes can still open voids - mention it to an inspector.

That works out to roughly 7 of Mesa County's 3,329 square miles on soluble rock, 7 of them with the rock at or near the surface. With about 161,260 residents (48 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 636 map points about 2.3 miles apart, so a pocket smaller than that can be missed or overstated.

Counties around Mesa County

The nearest county rated sinkhole country is Emery County, UT, about 121 miles west. None of the 6 closest counties land in the same band, so Mesa County stands out from its surroundings.

Delta County, CO 34 mi east · 0% at surface
Montrose County, CO 44 mi south · 1% at surface
Garfield County, CO 50 mi northeast · 15% at surface
Grand County, UT 60 mi west · 7% at surface
Rio Blanco County, CO 67 mi north · 1% at surface
San Miguel County, CO 70 mi south · under 1% at surface

The rock underneath

The largest mapped soluble unit here is the Hermosa Fm (sandstone), Pennsylvanian in age, covering about under 1% of the county. Next is the Hermosa Fm at under 1%.

The county also lies over the Paradox 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 Colorado

Mesa County ranks 39 of 64 in Colorado for soluble rock at the surface, and sits above 50% of US counties on that measure.