Sinkhole risk in Charles County, MD: 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: 15%
At or near the surface: 15%
Buried under cover: 0%

What to do about a house in Charles County

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

That works out to roughly 68 of Charles County's 458 square miles on soluble rock, 68 of them with the rock at or near the surface. With about 174,478 residents (381 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 492 map points about 1.0 miles apart, so a pocket smaller than that can be missed or overstated.

Counties around Charles County

The nearest county rated sinkhole country is Clarke County, VA, about 69 miles northwest. None of the 6 closest counties land in the same band, so Charles County stands out from its surroundings.

King George County, VA 16 mi southwest · 45% at surface
Stafford County, VA 24 mi west · 23% at surface
Alexandria city, VA 24 mi north · 0% at surface
Prince George's County, MD 26 mi north · 22% at surface
Calvert County, MD 26 mi east · 47% at surface
Westmoreland County, VA 28 mi southeast · 20% at surface

Which formation it is

The largest mapped soluble unit here is the Chesapeake Group; Calvert Formation (sand), Miocene in age, covering about 15% of the county.

Against the rest of Maryland

Charles County ranks 6 of 24 in Maryland for soluble rock at the surface, and sits above 71% of US counties on that measure.