Sinkhole risk in Montgomery County, AR: Mostly deep or small

Mostly deep or small

Some soluble rock, mostly deeply buried or in a small share of the county.

On soluble rock: 14%
At or near the surface: 14%
Buried under cover: 0%

The next step for one property

Sinkholes are uncommon here; watch for new depressions after heavy rain or leaking pipes.

That works out to roughly 106 of Montgomery County's 780 square miles on soluble rock, 106 of them with the rock at or near the surface. With about 8,510 residents (11 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 375 map points about 1.4 miles apart, so a pocket smaller than that can be missed or overstated.

Worth reading for this county: how these percentages are measured, and the warning signs that apply anywhere.

Counties around Montgomery County

The nearest county rated sinkhole country is Adair County, OK, about 109 miles northwest. 2 of the 6 closest counties land in the same band; the ground changes quickly around here.

Pike County, AR 27 mi south · 15% at surface
Garland County, AR 30 mi east · 12% at surface
Scott County, AR 31 mi northwest · 0% at surface
Polk County, AR 32 mi west · under 1% at surface
Yell County, AR 34 mi northeast · 0% at surface
Howard County, AR 37 mi southwest · 23% at surface

What Montgomery County is built on

The largest mapped soluble unit here is the Womble Shale (Middle Ordovician) (shale), Middle Ordovician in age, covering about 12% of the county. Next is the Collier Shale at 2%.

Against the rest of Arkansas

Montgomery County ranks 28 of 75 in Arkansas for soluble rock at the surface, and sits above 70% of US counties on that measure.