Sinkhole risk in Winchester city, VA: Sinkhole country

Sinkhole country

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

On soluble rock: 90%
At or near the surface: 90%
Buried under cover: 0%

What to do about a house in Winchester city

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

That works out to roughly 8 of Winchester city's 9 square miles on soluble rock, 8 of them with the rock at or near the surface. With about 27,800 residents (3,024 per square mile), there is effectively nowhere in the county off the soluble rock, town or country. The figures come from 520 map points about 0.1 miles apart, so a pocket smaller than that can be missed or overstated.

Worth reading for this county: the signs to look for and how an inspection works, and how these percentages are measured.

Counties around Winchester city

The closest county with no soluble rock mapped is Rappahannock County, VA, about 34 miles south. 2 of the 6 closest counties land in the same band; the ground changes quickly around here.

Frederick County, VA 5 mi northwest · 30% at surface
Clarke County, VA 11 mi east · 74% at surface
Warren County, VA 18 mi south · 23% at surface
Jefferson County, WV 19 mi northeast · 84% at surface
Berkeley County, WV 20 mi north · 44% at surface
Hampshire County, WV 25 mi west · 8% at surface

Which formation it is

The largest mapped soluble unit here is the Beekmantown Group (dolostone (dolomite)), Ordovician in age, covering about 46% of the county. Next is the Conococheague Formation at 31%.

Against the rest of Virginia

Winchester city ranks 4 of 133 in Virginia for soluble rock at the surface, and sits above 97% of US counties on that measure.