Sinkhole risk in Calvert County, MD: Pockets of it

Pockets of it

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

On soluble rock: 47%
At or near the surface: 47%
Buried under cover: 0%

The next step for one property

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 100 of Calvert County's 213 square miles on soluble rock, 100 of them with the rock at or near the surface. With about 94,913 residents (445 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 458 map points about 0.7 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 Calvert County

The nearest county rated sinkhole country is Clarke County, VA, about 89 miles northwest. 2 of the 6 closest counties land in the same band; the ground changes quickly around here.

St. Mary's County, MD 21 mi south · 15% at surface
Talbot County, MD 25 mi northeast · 5% at surface
Charles County, MD 26 mi west · 15% at surface
Dorchester County, MD 27 mi east · 0% at surface
Prince George's County, MD 27 mi northwest · 22% at surface
Westmoreland County, VA 32 mi southwest · 20% at surface

The rock underneath

The largest mapped soluble unit here is the Chesapeake Group; Calvert Formation (sand), Miocene in age, covering about 26% of the county. Next is the Chesapeake Group; Choptank Formation at 21%.

Against the rest of Maryland

Calvert County ranks 2 of 24 in Maryland for soluble rock at the surface, and sits above 86% of US counties on that measure.