Sinkhole risk in Prowers County, CO: Pockets of it

Pockets of it

Soluble rock at the surface or under thin cover in part of the county.

On soluble rock: 35%
At or near the surface: 35%
Buried under cover: 0%

What to do about a house in Prowers County

Check the parcel against your state survey sinkhole map, and ask for an inspection if cracks, depressions or sticking doors show up.

That works out to roughly 570 of Prowers County's 1,638 square miles on soluble rock, 570 of them with the rock at or near the surface. With about 11,957 residents (7 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 399 map points about 2.0 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 the signs to look for and how an inspection works.

Counties around Prowers County

The nearest county rated sinkhole country is Clark County, KS, about 150 miles east. 2 of the 6 closest counties land in the same band; the ground changes quickly around here.

Hamilton County, KS 33 mi east · 5% at surface
Kiowa County, CO 36 mi northwest · 30% at surface
Bent County, CO 37 mi west · 44% at surface
Stanton County, KS 43 mi southeast · 3% at surface
Baca County, CO 46 mi south · 6% at surface
Greeley County, KS 48 mi northeast · 7% 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 22% of the county. Next is the Niobrara Fm at 13%.

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

Prowers County ranks 4 of 64 in Colorado for soluble rock at the surface, and sits above 81% of US counties on that measure.