Sinkhole risk in Bland County, VA: Pockets of it

What to do about a house in Bland County

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 110 of Bland County's 358 square miles on soluble rock, 110 of them with the rock at or near the surface. With about 6,186 residents (17 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 464 map points about 0.9 miles apart, so a pocket smaller than that can be missed or overstated.

Two things to read before deciding: why gypsum and salt move faster than limestone, and the signs to look for and how an inspection works.

Counties around Bland County

The nearest county rated sinkhole country is Wythe County, VA, about 16 miles south, close enough that the same rock may run under the county line. 2 of the 6 closest counties land in the same band; the ground changes quickly around here.

• Wythe County, VA 16 mi south · 64% at surface
• Mercer County, WV 19 mi north · 39% at surface
• Pulaski County, VA 23 mi east · 57% at surface
• Tazewell County, VA 24 mi west · 43% at surface
• Giles County, VA 27 mi northeast · 65% at surface
• Smyth County, VA 30 mi southwest · 55% at surface

What Bland County is built on

The largest mapped soluble unit here is the Knox Group (dolostone (dolomite)), Cambrian-Ordovician in age, covering about 15% of the county. Next is the Moccasin or Bays Formation through Blackford Formation at 7%.

The county also lies over the Saltville, Virginia, a deep salt or gypsum basin. Deep beds rarely cause surface collapse on their own, but wells and mining into them have.

Against the rest of Virginia

Bland County ranks 37 of 133 in Virginia for soluble rock at the surface, and sits above 80% of US counties on that measure.

• Lexington city 100%
• Salem city 100%
• Roanoke city 98%
• Winchester city 90%
• Bristol city 89%