Sinkhole risk in Baltimore 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: 8%
At or near the surface: 8%
Buried under cover: 0%

What to do about a house in Baltimore County

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

That works out to roughly 45 of Baltimore County's 598 square miles on soluble rock, 45 of them with the rock at or near the surface. With about 852,425 residents (1,425 per square mile), most of the county is built up, so a mapped unit is likely to sit under somebody's street. The figures come from 595 map points about 1.0 miles apart, so a pocket smaller than that can be missed or overstated.

Counties around Baltimore County

The nearest county rated sinkhole country is Washington County, MD, about 65 miles west. 2 of the 6 closest counties land in the same band; the ground changes quickly around here.

Baltimore city, MD 10 mi south · 0% at surface
Harford County, MD 18 mi east · under 1% at surface
Howard County, MD 21 mi southwest · under 1% at surface
Carroll County, MD 23 mi west · 2% at surface
Kent County, MD 30 mi southeast · under 1% at surface
Anne Arundel County, MD 31 mi south · 15% at surface

Which formation it is

The largest mapped soluble unit here is the Cockeysville Marble (marble), Late Precambrian (?) in age, covering about 8% of the county.

Against the rest of Maryland

Baltimore County ranks 11 of 24 in Maryland for soluble rock at the surface, and sits above 66% of US counties on that measure.