Sinkhole risk in Ector County, TX: Sinkhole country

Sinkhole country

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

On soluble rock: 38%
At or near the surface: 38%
Buried under cover: 0%

What to do about a house in Ector County

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

That works out to roughly 338 of Ector County's 898 square miles on soluble rock, 338 of them with the rock at or near the surface. With about 170,022 residents (189 per square mile), homes are spread across towns and farmland, and a mapped unit may or may not reach the developed parts. The figures come from 396 map points about 1.5 miles apart, so a pocket smaller than that can be missed or overstated.

Counties around Ector County

The closest county with no soluble rock mapped is Archer County, TX, about 255 miles northeast. None of the 6 closest counties land in the same band, so Ector County stands out from its surroundings.

Crane County, TX 30 mi south · 16% at surface
Winkler County, TX 30 mi west · 12% at surface
Andrews County, TX 31 mi north · under 1% at surface
Midland County, TX 32 mi east · 16% at surface
Ward County, TX 41 mi southwest · 26% at surface
Martin County, TX 46 mi northeast · 3% at surface

Which formation it is

The largest mapped soluble unit here is the caliche deposits (evaporite), Pleistocene and Holocene in age, covering about 31% of the county. Next is the Fredericksburg Group at 4%.

31% 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 Texas

Ector County ranks 70 of 254 in Texas for soluble rock at the surface, and sits above 83% of US counties on that measure.