Sinkhole risk in Franklin County, VA: 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 to do about a house in Franklin County
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 3 of Franklin County's 691 square miles on soluble rock, 3 of them with the rock at or near the surface. With about 55,637 residents (81 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 266 map points about 1.6 miles apart, so a pocket smaller than that can be missed or overstated.
Read next: how these percentages are measured, and the warning signs that apply anywhere.
Counties around Franklin County
The nearest county rated sinkhole country is Roanoke city, VA, about 20 miles north, 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.
- Roanoke city, VA 20 mi north · 98% at surface
- Martinsville city, VA 21 mi south · 0% at surface
- Salem city, VA 22 mi northwest · 100% at surface
- Floyd County, VA 26 mi west · under 1% at surface
- Henry County, VA 26 mi south · under 1% at surface
- Roanoke County, VA 29 mi northwest · 33% at surface
Which formation it is
The largest mapped soluble unit here is the Alligator Back Formation - Banded marble (marble), Proterozoic Z-Cambrian in age, covering about under 1% of the county.
Against the rest of Virginia
Franklin County ranks 91 of 133 in Virginia for soluble rock at the surface, and sits above 52% of US counties on that measure.
- Lexington city 100%
- Salem city 100%
- Roanoke city 98%
- Winchester city 90%
- Bristol city 89%