Sinkhole risk in Marshall County, OK: Pockets of it

Pockets of it

Soluble rock at the surface or under thin cover in part of the county.

On soluble rock: 35%
At or near the surface: 35%
Buried under cover: 0%

What this means before you buy

Check the parcel against your state survey sinkhole map, and ask for an inspection if cracks, depressions or sticking doors show up.

That works out to roughly 131 of Marshall County's 371 square miles on soluble rock, 131 of them with the rock at or near the surface. With about 16,147 residents (43 per square mile), much of the land is open, and the mapped rock may sit far from where people actually live. The figures come from 295 map points about 1.1 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 Marshall County

The nearest county rated sinkhole country is Grady County, OK, about 94 miles northwest. 4 of the 6 closest counties land in the same band, so this is a regional pattern rather than a local quirk.

Johnston County, OK 21 mi north · 33% at surface
Love County, OK 28 mi west · 13% at surface
Grayson County, TX 28 mi south · 36% at surface
Bryan County, OK 29 mi east · 18% at surface
Carter County, OK 33 mi northwest · 11% at surface
Murray County, OK 36 mi northwest · 49% at surface

Which formation it is

The largest mapped soluble unit here is the Caddo Formation (limestone), Early Cretaceous in age, covering about 20% of the county. Next is the Kiamichi Formation at 8%.

Against the rest of Oklahoma

Marshall County ranks 21 of 77 in Oklahoma for soluble rock at the surface, and sits above 82% of US counties on that measure.