Sinkhole risk in Tuolumne County, CA: No soluble rock mapped

No soluble rock mapped

No soluble bedrock mapped.

On soluble rock: under 1%
At or near the surface: under 1%
Buried under cover: 0%

What this means before you buy

No soluble bedrock is mapped here, so natural sinkholes are unlikely. Collapses from broken pipes or old mines are a separate risk.

That works out to roughly 9 of Tuolumne County's 2,221 square miles on soluble rock, 9 of them with the rock at or near the surface. With about 53,893 residents (24 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 529 map points about 2.0 miles apart, so a pocket smaller than that can be missed or overstated.

Worth reading for this county: how these percentages are measured, and the warning signs that apply anywhere.

Counties around Tuolumne County

The nearest county rated sinkhole country is Emery County, UT, about 504 miles east. 5 of the 6 closest counties land in the same band, so this is a regional pattern rather than a local quirk.

Mariposa County, CA 31 mi south · 0% at surface
Calaveras County, CA 34 mi west · under 1% at surface
Alpine County, CA 42 mi north · 0% at surface
Amador County, CA 47 mi northwest · 0% at surface
Madera County, CA 57 mi south · 0% at surface
Mono County, CA 60 mi east · 2% at surface

The rock underneath

The largest mapped soluble unit here is the Limestone of probable Paleozoic or Mesozoic age (limestone), Paleozoic to Mesozoic in age, covering about under 1% of the county.

Against the rest of California

Tuolumne County ranks 25 of 58 in California for soluble rock at the surface, and sits above 52% of US counties on that measure.