Sinkhole risk in Baca County, CO: 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 148 of Baca County's 2,555 square miles on soluble rock, 148 of them with the rock at or near the surface. With about 3,367 residents (1 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 2.5 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 Baca County

The nearest county rated sinkhole country is Clark County, KS, about 150 miles east. 3 of the 6 closest counties land in the same band; the ground changes quickly around here.

Cimarron County, OK 39 mi south · 7% at surface
Morton County, KS 41 mi east · under 1% at surface
Stanton County, KS 45 mi northeast · 3% at surface
Prowers County, CO 46 mi north · 35% at surface
Bent County, CO 52 mi northwest · 44% at surface
Hamilton County, KS 63 mi northeast · 5% at surface

Which formation it is

The largest mapped soluble unit here is the Carlile Shale, Greenhorn Limestone, and Graneros Shale (shale), Cretaceous in age, covering about 5% of the county. Next is the Dockum Group at under 1%.

The county also lies over the Permian Basin, Anadarko Basin,Dalhart Basin, Palo Duro Basin, 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 Colorado

Baca County ranks 16 of 64 in Colorado for soluble rock at the surface, and sits above 64% of US counties on that measure.