Sinkhole risk in Logan County, KY: Sinkhole country

Sinkhole country

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

On soluble rock: 93%
At or near the surface: 93%
Buried under cover: 0%

What to do about a house in Logan County

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

That works out to roughly 515 of Logan County's 552 square miles on soluble rock, 515 of them with the rock at or near the surface. With about 28,467 residents (52 per square mile), there is effectively nowhere in the county off the soluble rock, town or country. The figures come from 307 map points about 1.3 miles apart, so a pocket smaller than that can be missed or overstated.

Worth reading for this county: the signs to look for and how an inspection works, and how these percentages are measured.

Counties around Logan County

The closest county with no soluble rock mapped is Hopkins County, KY, about 48 miles northwest. 4 of the 6 closest counties land in the same band, so this is a regional pattern rather than a local quirk.

Todd County, KY 17 mi west · 91% at surface
Simpson County, KY 18 mi southeast · 99% at surface
Robertson County, TN 23 mi south · 92% at surface
Butler County, KY 26 mi northeast · 20% at surface
Warren County, KY 27 mi east · 89% at surface
Muhlenberg County, KY 28 mi northwest · 4% at surface

Which formation it is

The largest mapped soluble unit here is the Rocks of Chesterian age, lower part (limestone), Upper Mississippian in age, covering about 49% of the county. Next is the Ste. Genevieve and St. Louis Limestones, undivided at 35%.

Against the rest of Kentucky

Logan County ranks 4 of 120 in Kentucky for soluble rock at the surface, and sits above 98% of US counties on that measure.