Sinkhole risk in Guadalupe County, TX: Mostly deep or small

Mostly deep or small

Some soluble rock, mostly deeply buried or in a small share of the county.

On soluble rock: 9%
At or near the surface: 9%
Buried under cover: 0%

What this means before you buy

Sinkholes are uncommon here; watch for new depressions after heavy rain or leaking pipes.

That works out to roughly 61 of Guadalupe County's 711 square miles on soluble rock, 61 of them with the rock at or near the surface. With about 195,166 residents (274 per square mile), homes are spread across towns and farmland, and a mapped unit may or may not reach the developed parts. The figures come from 524 map points about 1.2 miles apart, so a pocket smaller than that can be missed or overstated.

Two things to read before deciding: why gypsum and salt move faster than limestone, and how these percentages are measured.

Counties around Guadalupe County

The nearest county rated sinkhole country is Runnels County, TX, about 198 miles northwest. 1 of the 6 closest counties land in the same band; the ground changes quickly around here.

Comal County, TX 24 mi northwest · 92% at surface
Caldwell County, TX 26 mi northeast · 8% at surface
Gonzales County, TX 29 mi east · 0% at surface
Wilson County, TX 29 mi south · 0% at surface
Hays County, TX 33 mi north · 88% at surface
Bexar County, TX 36 mi west · 42% at surface

What Guadalupe County is built on

The largest mapped soluble unit here is the Pecan Gap Chalk (limestone), Late Cretaceous; Gulfian Series in age, covering about 6% of the county. Next is the Midway Group, undivided at 3%.

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

Guadalupe County ranks 118 of 254 in Texas for soluble rock at the surface, and sits above 67% of US counties on that measure.