Sinkhole risk in Trinity County, CA: Pockets of it

Pockets of it

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

On soluble rock: 25%
At or near the surface: 25%
Buried under cover: 0%

What this means before you buy

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 801 of Trinity County's 3,179 square miles on soluble rock, 801 of them with the rock at or near the surface. With about 15,642 residents (5 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 555 map points about 2.4 miles apart, so a pocket smaller than that can be missed or overstated.

Counties around Trinity County

The nearest county rated sinkhole country is Emery County, UT, about 667 miles east. None of the 6 closest counties land in the same band, so Trinity County stands out from its surroundings.

Humboldt County, CA 43 mi west · 3% at surface
Shasta County, CA 57 mi east · 9% at surface
Tehama County, CA 59 mi southeast · 1% at surface
Siskiyou County, CA 72 mi northeast · 9% at surface
Glenn County, CA 81 mi southeast · 0% at surface
Mendocino County, CA 86 mi south · 0% at surface

What Trinity County is built on

The largest mapped soluble unit here is the Paleozoic marine rocks, undivided, unit 9 (Western Klamath Mountains) (argillite), Devonian to Jurassic in age, covering about 25% of the county.

Against the rest of California

Trinity County ranks 1 of 58 in California for soluble rock at the surface, and sits above 77% of US counties on that measure.