SinkholeOdds

Sinkhole risk in Runnels County, TX: Sinkhole country

Sinkhole country

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

On soluble rock
52%
At or near the surface
52%
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 541 of Runnels County's 1,051 square miles on soluble rock, 541 of them with the rock at or near the surface. With about 9,751 residents (9 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 1.6 miles apart, so a pocket smaller than that can be missed or overstated.

Read next: why gypsum and salt move faster than limestone, and the signs to look for and how an inspection works.

Counties around Runnels County

The closest county with no soluble rock mapped is Archer County, TX, about 144 miles northeast. 2 of the 6 closest counties land in the same band; the ground changes quickly around here.

The rock underneath

The largest mapped soluble unit here is the Clear Fork Group (mudstone), Permian; Leonard Series in age, covering about 33% of the county. Next is the Lueders Formation at 8%.

34% of the county sits on gypsum or salt, which dissolves in years rather than millennia. That share matters more than its size suggests.

Against the rest of Texas

Runnels County ranks 49 of 254 in Texas for soluble rock at the surface, and sits above 88% of US counties on that measure.