Sinkhole risk in Allen County, KY: Sinkhole country

Sinkhole country

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

On soluble rock: 51%
At or near the surface: 51%
Buried under cover: 0%

The next step for one property

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

That works out to roughly 177 of Allen County's 344 square miles on soluble rock, 177 of them with the rock at or near the surface. With about 22,037 residents (64 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 259 map points about 1.2 miles apart, so a pocket smaller than that can be missed or overstated.

Counties around Allen County

The closest county with no soluble rock mapped is McLean County, KY, about 80 miles northwest. 5 of the 6 closest counties land in the same band, so this is a regional pattern rather than a local quirk.

Macon County, TN 18 mi southeast · 24% at surface
Barren County, KY 21 mi northeast · 67% at surface
Warren County, KY 21 mi northwest · 89% at surface
Simpson County, KY 22 mi west · 99% at surface
Sumner County, TN 24 mi southwest · 70% at surface
Trousdale County, TN 25 mi south · 85% at surface

Which formation it is

The largest mapped soluble unit here is the Salem, Warsaw, and Harrodsburg Limestones, undivided (limestone), Mississippian in age, covering about 38% of the county. Next is the Ste. Genevieve and St. Louis Limestones, undivided at 11%.

Against the rest of Kentucky

Allen County ranks 38 of 120 in Kentucky for soluble rock at the surface, and sits above 88% of US counties on that measure.