Sinkhole risk in Bastrop 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: 4%
At or near the surface: 4%
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 32 of Bastrop County's 888 square miles on soluble rock, 32 of them with the rock at or near the surface. With about 114,931 residents (129 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 561 map points about 1.3 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 how these percentages are measured.

Counties around Bastrop County

The nearest county rated sinkhole country is Runnels County, TX, about 199 miles northwest. 1 of the 6 closest counties land in the same band; the ground changes quickly around here.

Travis County, TX 25 mi northwest · 57% at surface
Lee County, TX 25 mi northeast · 0% at surface
Caldwell County, TX 27 mi southwest · 8% at surface
Fayette County, TX 28 mi southeast · 0% at surface
Williamson County, TX 42 mi northwest · 46% at surface
Hays County, TX 43 mi west · 88% at surface

What Bastrop County is built on

The largest mapped soluble unit here is the Midway Group, undivided (fine-grained mixed clastic), Paleocene in age, covering about 4% of the county.

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

Bastrop County ranks 127 of 254 in Texas for soluble rock at the surface, and sits above 61% of US counties on that measure.