SinkholeOdds

Sinkhole risk in Eddy County, NM: Sinkhole country

Sinkhole country

Fast-dissolving gypsum or salt beds under a large part of the county.

On soluble rock
41%
At or near the surface
41%
Buried under cover
0%

What this means before you buy

Get a sinkhole or geotechnical inspection before buying, building or adding weight to a foundation.

That works out to roughly 1,691 of Eddy County's 4,176 square miles on soluble rock, 1,691 of them with the rock at or near the surface. With about 61,436 residents (15 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 380 map points about 3.3 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 Eddy County

The closest county with no soluble rock mapped is Luna County, NM, about 202 miles west. 1 of the 6 closest counties land in the same band; the ground changes quickly around here.

Which formation it is

The largest mapped soluble unit here is the Grayburg and Queen Fromations (carbonate), Permian in age, covering about 7% of the county. Next is the Artesia Group at 7%.

30% 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 Permian Basin, Anadarko Basin,Dalhart Basin, Palo Duro 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

Eddy County ranks 4 of 33 in New Mexico for soluble rock at the surface, and sits above 84% of US counties on that measure.