Sinkhole risk in Callahan County, TX: Pockets of it

Pockets of it

Soluble rock at the surface or under thin cover in 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 Callahan County

Check the parcel against your state survey sinkhole map, and ask for an inspection if cracks, depressions or sticking doors show up.

That works out to roughly 338 of Callahan County's 899 square miles on soluble rock, 338 of them with the rock at or near the surface. With about 14,615 residents (16 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.

Counties around Callahan County

The nearest county rated sinkhole country is Taylor County, TX, about 30 miles west, close enough that the same rock may run under the county line. 4 of the 6 closest counties land in the same band, so this is a regional pattern rather than a local quirk.

Coleman County, TX 26 mi south · 36% at surface
Taylor County, TX 30 mi west · 66% at surface
Shackelford County, TX 31 mi north · 54% at surface
Eastland County, TX 31 mi east · 19% at surface
Brown County, TX 43 mi southeast · 19% at surface
Jones County, TX 43 mi northwest · 55% at surface

Which formation it is

The largest mapped soluble unit here is the Bead Mountain Formation (shale), Permian; Leonard Series in age, covering about 9% of the county. Next is the Admiral Formation at 9%.

Against the rest of Texas

Callahan County ranks 69 of 254 in Texas for soluble rock at the surface, and sits above 83% of US counties on that measure.