Sinkhole risk in McCurtain County, OK: 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: 6%
At or near the surface: 6%
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 111 of McCurtain County's 1,851 square miles on soluble rock, 111 of them with the rock at or near the surface. With about 30,805 residents (17 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 317 map points about 2.4 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 McCurtain County

The nearest county rated sinkhole country is Adair County, OK, about 123 miles north. 2 of the 6 closest counties land in the same band; the ground changes quickly around here.

Sevier County, AR 31 mi east · 26% at surface
Red River County, TX 38 mi southwest · 8% at surface
Polk County, AR 40 mi northeast · under 1% at surface
Pushmataha County, OK 41 mi northwest · 0% at surface
Little River County, AR 42 mi southeast · 4% at surface
Howard County, AR 44 mi east · 23% at surface

The rock underneath

The largest mapped soluble unit here is the Caddo Formation (limestone), Early Cretaceous in age, covering about 2% of the county. Next is the Kiamichi Formation 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 Oklahoma

McCurtain County ranks 52 of 77 in Oklahoma for soluble rock at the surface, and sits above 64% of US counties on that measure.