SinkholeOdds

Sinkhole risk in Foard County, TX: Sinkhole country

Sinkhole country

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

On soluble rock
72%
At or near the surface
72%
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 504 of Foard County's 704 square miles on soluble rock, 504 of them with the rock at or near the surface. With about 1,053 residents (1 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 243 map points about 1.7 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 Foard County

The closest county with no soluble rock mapped is Tillman County, OK, about 58 miles northeast. 6 of the 6 closest counties land in the same band, so this is a regional pattern rather than a local quirk.

What Foard County is built on

The largest mapped soluble unit here is the Blaine Formation (mudstone), Permian; Guadalupe Series in age, covering about 35% of the county. Next is the Clear Fork Group at 26%.

72% 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

Foard County ranks 22 of 254 in Texas for soluble rock at the surface, and sits above 93% of US counties on that measure.