Sinkhole risk in Rockingham County, VA: Pockets of it

Pockets of it

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

On soluble rock: 45%
At or near the surface: 45%
Buried under cover: 0%

The next step for one property

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 381 of Rockingham County's 850 square miles on soluble rock, 381 of them with the rock at or near the surface. With about 87,674 residents (103 per square mile), homes are spread across towns and farmland, and a mapped unit may or may not reach the developed parts. The figures come from 496 map points about 1.3 miles apart, so a pocket smaller than that can be missed or overstated.

Two things to read before deciding: the signs to look for and how an inspection works, and how these percentages are measured.

Counties around Rockingham County

The nearest county rated sinkhole country is Harrisonburg city, VA, about 5 miles south, close enough that the same rock may run under the county line. 3 of the 6 closest counties land in the same band; the ground changes quickly around here.

Harrisonburg city, VA 5 mi south · 85% at surface
Page County, VA 23 mi east · 37% at surface
Staunton city, VA 26 mi south · 89% at surface
Greene County, VA 27 mi southeast · 0% at surface
Augusta County, VA 27 mi southwest · 49% at surface
Pendleton County, WV 27 mi northwest · 19% at surface

Which formation it is

The largest mapped soluble unit here is the Beekmantown Group (dolostone (dolomite)), Ordovician in age, covering about 18% of the county. Next is the Conococheague Formation at 9%.

Against the rest of Virginia

Rockingham County ranks 27 of 133 in Virginia for soluble rock at the surface, and sits above 86% of US counties on that measure.