Annapolis, Maryland: Firmly in the Atlantic Coastal Plain

Yes. Annapolis, the capital of Maryland, sits squarely within the Atlantic Coastal Plain physiographic province.

Geologic Context

• Region: Extends from Cape Cod, MA to the Florida Keys—broad, low-lying terraces of unconsolidated sediments.
• Underlying Strata: Cretaceous and Tertiary sediments—sand, gravel, clay, marl, shelly deposits (Calvert, Choptank, St. Marys formations). Fossil-rich (shark teeth, mollusks).
• Topography: Gently rolling, 0–100 ft (0–30 m) elevation. Annapolis averages ~30 ft (9 m).
• Hydrology: Tidal rivers (Severn, South, Magothy) dissect the plain into peninsulas ("necks")—defining Annapolis's maritime layout.

Contrast: The Fall Line

Just 15–20 miles west/northwest (near Bowie, Laurel, BWI Airport), the Atlantic Seaboard Fall Line marks the boundary with the Piedmont Plateau—hard crystalline bedrock, rapids, higher relief. Annapolis is east of this line, fully in the Coastal Plain.

Implications

• Soils: Sandy, acidic, well-drained—historically tobacco, now forest/suburban.
• Water: Shallow aquifers (Magothy, Aquia); saltwater intrusion risk.
• Climate: Moderated by Chesapeake Bay—milder winters, humid summers.
• Development: Low density, septic systems common; sea-level rise vulnerability (nuisance flooding increasing).

Annapolis is a classic Coastal Plain tidewater capital—like Williamsburg, Dover, Wilmington, Charleston.