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Part of the NPS Geodiversity Atlas, which describes each park's significant geologic features and processes. Geodiversity is the full variety of a park's natural geologic resources — rocks, minerals, sediments, fossils, landforms and physical processes — and its soils. The atlas comes from the NPS Geologic Resources Inventory.
The park's Geologic Resources Inventory report. Image from the NPS's page.
The park
Prince William Forest Park, about 56 km (35 mi) south of Washington, D.C., in Prince William County, Virginia, began in 1933 as the Chopawamsic Recreational Demonstration Area, part of Franklin D. Roosevelt's New Deal; it got its present name on June 22, 1948. Its 6,507 hectares (16,081 acres) hold the largest protected eastern Piedmont forest in the United States.
It was a model for the New Deal's recreational demonstration areas, parks built so low-income city children and families could get out into nature. The Civilian Conservation Corps and Works Progress Administration, which also aimed to reduce unemployment and teach skills, built its roads, bridges, dams and cabin camps — the largest concentration of CCC and WPA structures in the National Park System.
Geologic setting
The park straddles the Fall Line, the boundary between the Piedmont and the Atlantic Coastal Plain. Its rolling hills, narrow ridges and steep ravines express the rock beneath. The bedrock is a mix of volcanic, sedimentary and plutonic rocks, buried and metamorphosed during the Alleghenian Orogeny, then uplifted and eroded to a plateau.
| Age | Rocks |
|---|---|
| Neoproterozoic–Cambrian (oldest) | mafic and ultramafic rocks along and north of Quantico Creek |
| Ordovician | the Lake Jackson pluton, and the Quantico, Lunga Reservoir and Chopawamsic Formations, widespread in the park |
| Silurian | felsic igneous rocks intruded into the Chopawamsic Formation in the east |
| Cretaceous to Pleistocene | a veneer of Coastal Plain sediments: the Potomac Formation, Miocene terraces, and Pleistocene river and estuary deposits |
| Quaternary | terrace deposits and alluvium |
Geologic map of the park, from the Geologic Resources Inventory. NPS.
The park shares its geologic history with the wider Piedmont and Coastal Plain provinces. Its Geologic Resources Inventory maps and reports are in the NPS DataStore, and a Soil Resources Inventory project has been completed.
South Fork Quantico Creek. Image from the NPS's page.
Sources
Based on "NPS Geodiversity Atlas—Prince William Forest Park, Virginia," National Park Service; a work of the United States government in the public domain. It cites Thornberry-Ehrlich (2009), Southworth and Denenny (2006) and the National Park Service (2014).
Dans ces publicationsPrince William Forest Park
Licence : CC0 1.0 (domaine public) · Adapté de www.nps.gov
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