SinkholeOdds

Sinkhole risk in Hardeman County, TX: Sinkhole country

Sinkhole country

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

On soluble rock
63%
At or near the surface
63%
Buried under cover
0%

The next step for one property

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

That works out to roughly 436 of Hardeman County's 695 square miles on soluble rock, 436 of them with the rock at or near the surface. With about 3,417 residents (5 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 255 map points about 1.7 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 Hardeman County

The closest county with no soluble rock mapped is Tillman County, OK, about 47 miles east. 6 of the 6 closest counties land in the same band, so this is a regional pattern rather than a local quirk.

The rock underneath

The largest mapped soluble unit here is the Blaine Formation (mudstone), Permian; Guadalupe Series in age, covering about 52% of the county. Next is the Clear Fork Group at 6%.

63% 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

Hardeman County ranks 33 of 254 in Texas for soluble rock at the surface, and sits above 91% of US counties on that measure.