SinkholeOdds

Sinkhole risk in Stephens County, OK: 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
9%
At or near the surface
9%
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 79 of Stephens County's 870 square miles on soluble rock, 79 of them with the rock at or near the surface. With about 44,075 residents (51 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 384 map points about 1.5 miles apart, so a pocket smaller than that can be missed or overstated.

Two things to read before deciding: why gypsum and salt move faster than limestone, and how these percentages are measured.

Counties around Stephens County

The nearest county rated sinkhole country is Grady County, OK, about 37 miles north, close enough that the same rock may run under the county line. 2 of the 6 closest counties land in the same band; the ground changes quickly around here.

What Stephens County is built on

The largest mapped soluble unit here is the Terrace Deposits (sand), Pleistocene in age, covering about 5% of the county. Next is the Marlow Formation at 2%.

9% of the county sits on gypsum or salt, which dissolves in years rather than millennia. That share matters more than its size suggests.

Against the rest of Oklahoma

Stephens County ranks 48 of 77 in Oklahoma for soluble rock at the surface, and sits above 67% of US counties on that measure.