Sinkhole risk in Donley County, TX: Sinkhole country

Sinkhole country

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

On soluble rock: 28%
At or near the surface: 28%
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 260 of Donley County's 927 square miles on soluble rock, 260 of them with the rock at or near the surface. With about 3,193 residents (3 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 400 map points about 1.5 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 Donley County

The closest county with no soluble rock mapped is Hemphill County, TX, about 67 miles northeast. 3 of the 6 closest counties land in the same band; the ground changes quickly around here.

Armstrong County, TX 31 mi west · 27% at surface
Collingsworth County, TX 31 mi east · 59% at surface
Gray County, TX 31 mi north · 2% at surface
Briscoe County, TX 37 mi southwest · 42% at surface
Hall County, TX 37 mi south · 69% at surface
Carson County, TX 44 mi northwest · under 1% at surface

The rock underneath

The largest mapped soluble unit here is the Whitehorse Group, undivided (sandstone), Permian; Guadalupe Series in age, covering about 12% of the county. Next is the Quartermaster Formation and Whitehorse Group, undivided at 12%.

28% 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

Donley County ranks 86 of 254 in Texas for soluble rock at the surface, and sits above 78% of US counties on that measure.