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NPS Geodiversity Atlas—Manassas National Battlefield Park, Virginia

Geodiversity refers to the full variety of natural geologic (rocks, minerals, sediments, fossils, landforms, and physical processes) and soil resources and processes that occur in the park. A product of the Geologic Resources Inventory, the NPS Geodiversity Atlas delivers information in support of education, Geoconservation, and integrated management of living (biotic) and non-living (abiotic) components of the ecosystem.

image of park gri report cover with photo of a cannon
In-depth geologic information is contained in the baseline inventory products of the Geologic Resources Inventory, see table below.

Introduction

Manassas National Battlefield Park (MANA) is located approximately 40 km (25 mi) west of Washington, D.C. in Fairfax and Prince William Counties, Virginia. Designated on May 10, 1940, MANA encompasses about 2,052 hectares (5,073 acres) and was established to preserve the land and resources associated with the First and Second Battles of Manassas (First and Second Battles of Bull Run) during the American Civil War. The Battle of First Manassas was fought on July 21, 1861, and represents one of the first major land battles of the Civil War. Although the battle ended in a Confederate victory, a sobering number of casualties resulted for both sides. The Battle of First Manassas is where Confederate Brigadier General Thomas J. Jackson rose to prominence and acquired his nickname “Stonewall”. The Battle of Second Manassas on August 28–30, 1862, resulted in another Union defeat and shifted the seat of war from the gates of Richmond, Virginia, to the doorsteps of Washington, D.C., and paved the way for Robert E. Lee’s first invasion of the North (National Park Service 2014b). MANA preserves the battlefield landscape as it existed at the time of the Civil War and includes three houses that date from the Civil War period, several post-war historic buildings, a Confederate cemetery, the reconstructed Stone Bridge over Bull Run, approximately 10 km (6 mi) of historic road traces, historic structures, archeological resources, cemeteries, trenches, earthworks, forests, and open pasturelands.

Geologic Setting

Manassas National Battlefield Park is situated in the Culpeper Basin of the western Piedmont physiographic province, a distinctive region characterized by relatively low relief, gently rolling hills, and flat fields. The Culpeper Basin is one of a series of trough-like depressions that formed due to extensional tectonics as the Atlantic Ocean opened about 200 million years ago (Southworth and Denenny 2006). As the basin formed it was filled with Triassic- and Jurassic-age sediments derived from the Newark Supergroup. Lithological variations have shaped the landscape expression of MANA and created subtle yet important topographic expressions that were utilized during the First and Second Battles of Manassas for strategic defenses, troop movements, and transport routes (Thornberry-Ehrlich 2008a). The bedrock underlying MANA consists predominantly of red siltstone, shale (mudstone), and lacustrine clay of the Triassic Groveton Member of the Bull Run Formation. Mapped in the western portion of MANA are Triassic–Jurassic-age metamorphic rocks that have been intruded by diabase dikes and sills. The hot, molten diabase thermally metamorphosed the red siltstone to gray hornfels near the contact (Southworth and Denenny 2006). Subsequent uplift and erosion formed younger surficial units consisting of low-level terrace deposits and extensive alluvium.

Regional Geology

Manassas National Battlefield is a part of the Piedment Physiographic Province and shares its geologic history and some characteristic geologic formations with a region that extends well beyond park boundaries.

Maps and Reports

image of park gri geologic map

The Geologic Resources Inventory produces digital geologic maps and reports for more than 270 natural resource parks. The products listed below are currently available for this park, check back often for updates as many maps, reports, and posters are still in progress.
  • Scoping summaries are records of scoping meetings where NPS staff and local geologists determined the park’s geologic mapping plan and what content should be included in the report.
  • Digital geologic maps include files for viewing in GIS software, a guide to using the data, and a document with ancillary map information. Newer products also include data viewable in Google Earth and online map services.
  • Reports use the maps to discuss the park’s setting and significance, notable geologic features and processes, geologic resource management issues, and geologic history.
  • Posters are a static view of the GIS data in PDF format. Newer posters include aerial imagery or shaded relief and other park information. They are also included with the reports.
  • Projects list basic information about the program and all products available for a park.

Source: Data Store Saved Search 3010. To search for additional information, visit the Data Store.

A NPS Soil Resources Inventory project has been completed for Manassas National Battlefield Park and can be found on the NPS Data Store.

Source: Data Store Saved Search 3057. To search for additional information, visit the Data Store.

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Manassas National Battlefield Park

National Park Service Geodiversity Atlas

The servicewide Geodiversity Atlas provides information on geoheritage and geodiversity resources and values within the National Park System. This information supports science-based geoconservation and interpretation in the NPS, as well as STEM education in schools, museums, and field camps. The NPS Geologic Resources Division and many parks work with National and International geoconservation communities to ensure that NPS abiotic resources are managed using the highest standards and best practices available.


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Manassas National Battlefield Park

Last updated: July 10, 2024