SinkholeOdds

Sinkhole risk in Fisher County, TX: Sinkhole country

Sinkhole country

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

On soluble rock
59%
At or near the surface
59%
Buried under cover
0%

What to do about a house in Fisher County

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

That works out to roughly 533 of Fisher County's 899 square miles on soluble rock, 533 of them with the rock at or near the surface. With about 3,665 residents (4 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 396 map points about 1.5 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 Fisher County

The closest county with no soluble rock mapped is Archer County, TX, about 116 miles northeast. 4 of the 6 closest counties land in the same band, so this is a regional pattern rather than a local quirk.

What Fisher County is built on

The largest mapped soluble unit here is the Whitehorse Group, undivided (sandstone), Permian; Guadalupe Series in age, covering about 35% of the county. Next is the Blaine Formation at 11%.

53% 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

Fisher County ranks 34 of 254 in Texas for soluble rock at the surface, and sits above 90% of US counties on that measure.