Sinkhole risk in Platte County, WY: 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: 8%
At or near the surface: 8%
Buried under cover: 0%

What to do about a house in Platte County

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

That works out to roughly 167 of Platte County's 2,081 square miles on soluble rock, 167 of them with the rock at or near the surface. With about 8,512 residents (4 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 398 map points about 2.3 miles apart, so a pocket smaller than that can be missed or overstated.

Counties around Platte County

The nearest county rated sinkhole country is Dawes County, NE, about 101 miles northeast. 3 of the 6 closest counties land in the same band; the ground changes quickly around here.

Goshen County, WY 31 mi east · 1% at surface
Albany County, WY 51 mi southwest · 12% at surface
Laramie County, WY 60 mi south · under 1% at surface
Converse County, WY 66 mi northwest · under 1% at surface
Sioux County, NE 67 mi east · 13% at surface
Scotts Bluff County, NE 67 mi east · 0% at surface

The rock underneath

The largest mapped soluble unit here is the Hartville Formation (sandstone), Lower Pennsylvanian-Permian in age, covering about 5% of the county. Next is the Wells and Amsden Formations (TB), or Casper Formation and Madison Limestone (N, S) at 2%.

The county also lies over the Northern Denver 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 Wyoming

Platte County ranks 15 of 23 in Wyoming for soluble rock at the surface, and sits above 66% of US counties on that measure.