Sinkhole risk in Cibola County, NM: Pockets of it

Pockets of it

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

On soluble rock: 29%
At or near the surface: 29%
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 1,308 of Cibola County's 4,540 square miles on soluble rock, 1,308 of them with the rock at or near the surface. With about 26,686 residents (6 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 309 map points about 3.8 miles apart, so a pocket smaller than that can be missed or overstated.

Worth reading for this county: why gypsum and salt move faster than limestone, and the signs to look for and how an inspection works.

Counties around Cibola County

The nearest county rated sinkhole country is Eddy County, NM, about 272 miles southeast. 2 of the 6 closest counties land in the same band; the ground changes quickly around here.

McKinley County, NM 48 mi north · 13% at surface
Valencia County, NM 69 mi east · 13% at surface
Catron County, NM 74 mi south · 1% at surface
Bernalillo County, NM 75 mi east · 6% at surface
Sandoval County, NM 82 mi northeast · 18% at surface
Socorro County, NM 88 mi southeast · 23% at surface

What Cibola County is built on

The largest mapped soluble unit here is the Chinle Group (medium-grained mixed clastic), Triassic in age, covering about 10% of the county. Next is the Rio Salado Tongue of Mancos Shale at 4%.

16% 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 Holbrook 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 New Mexico

Cibola County ranks 5 of 33 in New Mexico for soluble rock at the surface, and sits above 79% of US counties on that measure.