Sinkhole risk in Union County, MS: Sinkhole country

Sinkhole country

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

On soluble rock: 75%
At or near the surface: 75%
Buried under cover: 0%

What to do about a house in Union County

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

That works out to roughly 313 of Union County's 416 square miles on soluble rock, 313 of them with the rock at or near the surface. With about 28,363 residents (68 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 341 map points about 1.1 miles apart, so a pocket smaller than that can be missed or overstated.

Counties around Union County

The closest county with no soluble rock mapped is Yalobusha County, MS, about 51 miles southwest. 3 of the 6 closest counties land in the same band; the ground changes quickly around here.

Pontotoc County, MS 18 mi south · 82% at surface
Tippah County, MS 20 mi north · 60% at surface
Lee County, MS 23 mi southeast · 62% at surface
Benton County, MS 25 mi northwest · 2% at surface
Prentiss County, MS 29 mi east · 24% at surface
Lafayette County, MS 29 mi west · 1% at surface

What Union County is built on

The largest mapped soluble unit here is the Ripley formation (sand), Upper Cretaceous in age, covering about 30% of the county. Next is the Porters Creek formation at 28%.

Against the rest of Mississippi

Union County ranks 6 of 82 in Mississippi for soluble rock at the surface, and sits above 94% of US counties on that measure.