Sinkhole risk in Fannin 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: 25%
At or near the surface: 25%
Buried under cover: 0%

The next step for one property

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 217 of Fannin County's 878 square miles on soluble rock, 217 of them with the rock at or near the surface. With about 38,650 residents (44 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 324 map points about 1.6 miles apart, so a pocket smaller than that can be missed or overstated.

Counties around Fannin County

The nearest county rated sinkhole country is Grady County, OK, about 142 miles northwest. 3 of the 6 closest counties land in the same band; the ground changes quickly around here.

Bryan County, OK 27 mi north · 18% at surface
Delta County, TX 29 mi southeast · 4% at surface
Lamar County, TX 31 mi east · 7% at surface
Hunt County, TX 32 mi south · 2% at surface
Grayson County, TX 33 mi west · 36% at surface
Collin County, TX 39 mi southwest · 47% at surface

What Fannin County is built on

The largest mapped soluble unit here is the Gober Chalk and Roxton Limestone (limestone), Late Cretaceous; Gulfian Series in age, covering about 22% of the county. Next is the Ector Chalk at 2%.

The county also lies over the Gulf Coast salt domes, 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

Fannin County ranks 91 of 254 in Texas for soluble rock at the surface, and sits above 77% of US counties on that measure.