Sinkhole risk in Sharp County, AR: Sinkhole country

Sinkhole country

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

On soluble rock: 100%
At or near the surface: 100%
Buried under cover: 0%

What to do about a house in Sharp County

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

That works out to roughly 603 of Sharp County's 605 square miles on soluble rock, 603 of them with the rock at or near the surface. With about 18,130 residents (30 per square mile), there is effectively nowhere in the county off the soluble rock, town or country. The figures come from 584 map points about 1.0 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 Sharp County

The closest county with no soluble rock mapped is Jackson County, AR, about 42 miles south. 4 of the 6 closest counties land in the same band, so this is a regional pattern rather than a local quirk.

Lawrence County, AR 23 mi southeast · 37% at surface
Fulton County, AR 24 mi northwest · 100% at surface
Izard County, AR 25 mi west · 100% at surface
Randolph County, AR 27 mi northeast · 60% at surface
Independence County, AR 31 mi south · 41% at surface
Oregon County, MO 36 mi north · 100% at surface

What Sharp County is built on

The largest mapped soluble unit here is the Cotter and Jefferson City Dolomites (dolostone (dolomite)), Early Ordovician in age, covering about 43% of the county. Next is the St. Peter Sanstone and Everton Formation (Middle Ordovician) at 33%.

Against the rest of Arkansas

Sharp County ranks 2 of 75 in Arkansas for soluble rock at the surface, and sits above 99% of US counties on that measure.