Sinkhole risk in Harrisonburg city, VA: Sinkhole country

Sinkhole country

Soluble rock at or near the surface across much of the county.

On soluble rock: 85%
At or near the surface: 85%
Buried under cover: 0%

What this means before you buy

Get a sinkhole or geotechnical inspection before buying, building or adding weight to a foundation.

That works out to roughly 15 of Harrisonburg city's 17 square miles on soluble rock, 15 of them with the rock at or near the surface. With about 51,164 residents (2,951 per square mile), most of the county is built up, so a mapped unit is likely to sit under somebody's street. The figures come from 506 map points about 0.2 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 Harrisonburg city

The closest county with no soluble rock mapped is Greene County, VA, about 24 miles southeast. 2 of the 6 closest counties land in the same band; the ground changes quickly around here.

Rockingham County, VA 5 mi north · 45% at surface
Staunton city, VA 22 mi southwest · 89% at surface
Augusta County, VA 23 mi southwest · 49% at surface
Greene County, VA 24 mi southeast · 0% at surface
Page County, VA 24 mi northeast · 37% at surface
Waynesboro city, VA 26 mi south · 69% at surface

The rock underneath

The largest mapped soluble unit here is the Beekmantown Group (dolostone (dolomite)), Ordovician in age, covering about 46% of the county. Next is the Edinburg Formation, Lincolnshire and New Market Limestones at 39%.

Against the rest of Virginia

Harrisonburg city ranks 7 of 133 in Virginia for soluble rock at the surface, and sits above 96% of US counties on that measure.