Sinkhole risk in Oldham County, KY: 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: 88%
Buried under cover: 3%

What to do about a house in Oldham County

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

That works out to roughly 169 of Oldham County's 187 square miles on soluble rock, 164 of them with the rock at or near the surface. With about 70,525 residents (377 per square mile), there is effectively nowhere in the county off the soluble rock, town or country. The figures come from 258 map points about 0.9 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 Oldham County

The closest county with no soluble rock mapped is Brown County, IN, about 69 miles northwest. 2 of the 6 closest counties land in the same band; the ground changes quickly around here.

Clark County, IN 15 mi west · 3% at surface
Trimble County, KY 16 mi north · 16% at surface
Shelby County, KY 17 mi southeast · 68% at surface
Jefferson County, KY 18 mi southwest · 59% at surface
Henry County, KY 19 mi east · 48% at surface
Scott County, IN 25 mi northwest · 2% at surface

What Oldham County is built on

The largest mapped soluble unit here is the Drakes Formation (dolostone (dolomite)), Ordovician in age, covering about 43% of the county. Next is the Laurel Dolomite, Osgood Formation, and Brassfield Dolomite, undivided at 24%.

Against the rest of Kentucky

Oldham County ranks 14 of 120 in Kentucky for soluble rock at the surface, and sits above 96% of US counties on that measure.