Geology of George Washington Memorial Parkway

George Washington Memorial Parkway is a 45 km (28 mi) scenic road and park system along the Potomac River through Maryland (Montgomery County), Virginia (Alexandria, Arlington and Fairfax) and Washington, D.C.

• Authorized: May 29, 1930, as a memorial to the first president.
• Size: 2,847 hectares (7,035 acres).
• Route: from Mount Vernon, Washington's home, past the capital he founded, to the Great Falls of the Potomac, where he showed his skill as an engineer.
• A design first: parts of it were the first comprehensively designed modern motorway built as a landscaped, park-like road, pioneering limited access, grade-separated intersections and cloverleaf interchanges.
• Along the way (north to south): Great Falls Park, Turkey Run Park, Claude Moore Colonial Farm, Fort Marcy, Theodore Roosevelt Island, the U.S. Marine Corps War Memorial, the Netherlands Carillon, Arlington Memorial Bridge and Memorial Avenue, the Women in Military Service for America Memorial, Arlington House, Lady Bird Johnson Park, the LBJ Memorial Grove, Dyke Marsh Wildlife Preserve and Fort Hunt Park.

The parkway beside the Potomac. NPS.

Geologic setting

The parkway straddles two provinces — the Piedmont and the Atlantic Coastal Plain — with rolling hills, river terraces, riverside marshes and inlets following the Potomac toward Chesapeake Bay. Its rocks span the Precambrian to the Pleistocene ice ages.

Three mountain-building events metamorphosed and deformed the bedrock:

The rising Appalachians were eroded, and their sediment spread east in a thick wedge toward the Atlantic — the Coastal Plain.

The rocks, oldest to youngest:

• Neoproterozoic–Cambrian: the Mather Gorge Formation and other metasedimentary and meta-igneous rocks.
• Paleozoic: the Cambrian Sykesville Formation; Ordovician igneous and metamorphic rocks of the Dalecarlia and Georgetown intrusive suites; the Bear Island Granodiorite and Clarendon Granite.
• Mesozoic and Cenozoic: the Cretaceous Potomac Formation, the Paleocene Brightseat and Aquia formations, and abundant Quaternary alluvium and terrace deposits.

The Geologic Resources Inventory map of the parkway (southern section). NPS.

Protected and hazardous

• Fossils: all NPS fossil resources are protected under the Paleontological Resources Preservation Act of 2009.
• Abandoned mineral lands: old mine sites can be valuable cultural resources and habitat, but many endanger visitors and wildlife and harm water and landscapes. Stay out and stay alive.

Inventories

• Geologic Resources Inventory: digital geologic maps and reports for more than 270 natural resource parks; this park's are listed on the NPS DataStore.
• Soil Resources Inventory: completed for the parkway and on the DataStore.

This page is part of the NPS Geodiversity Atlas. More: the parkway · plate tectonics · geologic time · Virginia Division of Geology and Mineral Resources · Maryland Geological Survey

Sources

Based on "NPS Geodiversity Atlas—George Washington Memorial Parkway," National Park Service, citing National Park Service (2014, 2016), Thornberry-Ehrlich (2009), Drake and Froelich (1997) and Southworth and Denenny (2006); a work of the United States government in the public domain. The original's title names West Virginia; the parkway is in Virginia, as its text and geologic map say. A picture of the GRI report's cover is left out.