Sinkhole risk in Lamar 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: 7%
At or near the surface: 7%
Buried under cover: 0%

What to do about a house in Lamar County

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

That works out to roughly 63 of Lamar County's 907 square miles on soluble rock, 63 of them with the rock at or near the surface. With about 51,249 residents (56 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 318 map points about 1.7 miles apart, so a pocket smaller than that can be missed or overstated.

Counties around Lamar County

The nearest county rated sinkhole country is Cherokee County, OK, about 158 miles north. 2 of the 6 closest counties land in the same band; the ground changes quickly around here.

Delta County, TX 20 mi south · 4% at surface
Choctaw County, OK 25 mi north · 30% at surface
Red River County, TX 30 mi east · 8% at surface
Fannin County, TX 31 mi west · 25% at surface
Hopkins County, TX 36 mi south · 24% at surface
Franklin County, TX 40 mi southeast · 31% at surface

What Lamar 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 6% of the county. Next is the Pecan Gap Chalk at under 1%.

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

Lamar County ranks 121 of 254 in Texas for soluble rock at the surface, and sits above 65% of US counties on that measure.