The Bull Run Mountains are a mountain range of the

Blue Ridge Mountains The Blue Ridge Mountains are a physiographic province of the larger Appalachian Mountains range. The mountain range is located in the Eastern United States, and extends 550 miles southwest from southern Pennsylvania through Maryland, West Virgin ...

in northern

Virginia Virginia, officially the Commonwealth of Virginia, is a state in the Mid-Atlantic and Southeastern regions of the United States, between the Atlantic Coast and the Appalachian Mountains. The geography and climate of the Commonwealth ar ...

in the

United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territorie ...

. Located approximately east of the main chain, across the

Loudoun Valley The Loudoun Valley is a small, but historically significant valley in the Blue Ridge Mountains located in Loudoun County in Northern Virginia in the United States. Geography The lush and fertile valley lies between Catoctin Mountain and the B ...

. The Bull Run Mountains, together with

Catoctin Mountain Catoctin Mountain, along with the geologically associated Bull Run Mountains, forms the easternmost mountain ridge of the Blue Ridge Mountains, which are in turn a part of the Appalachian Mountains range. The ridge runs northeast–southwest for ...

in Virginia and

Maryland Maryland ( ) is a state in the Mid-Atlantic region of the United States. It shares borders with Virginia, West Virginia, and the District of Columbia to its south and west; Pennsylvania to its north; and Delaware and the Atlantic Ocean to ...

, make up the easternmost front of the Blue Ridge. The mountain range is the home of the Virginia Outdoors Foundation's Preserve at Bull Run Mountains, which is a state-designated Natural Area Preserve dedicated to the scientific and educational potential of the region. The Preserve at Bull Run Mountains has over seven miles of trails that are open to the public on Fridays, Saturdays, and Sundays - year round. The mountain range also holds several communities of residents, which includes the Bull Run Mountain Estates.

Interstate 66 Interstate 66 (I-66) is an east–west Interstate Highway in the eastern United States. It runs from an interchange with I-81 near Middletown, Virginia, on its western end to an interchange with U.S. Route 29 (US 29) in Washingt ...

, the John Marshall Highway (

Virginia Route 55 State Route 55 (SR 55) is a primary state highway in the U.S. state of Virginia. Known for most of its length as John Marshall Highway, the state highway runs from the West Virginia state line, where the highway continues as West Virginia Rout ...

) and the

Manassas Gap Railroad The Manassas Gap Railroad (MGRR) ran from Mount Jackson, Virginia, to the Orange and Alexandria Railroad's Manassas Junction, which later became the city of Manassas, Virginia. Chartered by the Virginia General Assembly in 1850, the MGRR was a n ...

pass through the range at Thoroughfare Gap.

Geography

The range extends in a southwest–northeast orientation for approximately from Aldie in

Loudoun County Loudoun County () is in the northern part of the Commonwealth of Virginia in the United States. In 2020, the census returned a population of 420,959, making it Virginia's third-most populous county. Loudoun County's seat is Leesburg. Loudoun C ...

, through western

Prince William County Prince William County is located on the Potomac River in the U.S. state of Virginia. As of the 2020 census, the population sits at 482,204, making it Virginia's second-most populous county. Its county seat is the independent city of Manassas ...

to New Baltimore in

Fauquier County Fauquier is a county in the Commonwealth of Virginia. As of the 2020 census, the population was 72,972. The county seat is Warrenton. Fauquier County is in Northern Virginia and is a part of the Washington metropolitan area. History In 160 ...

. In the north, from Aldie to the headwaters of

Bull Run Creek Bull Run Creek is a stream in the U.S. state of South Dakota. Bull Run Creek was named for an incident when a runaway bull roamed the area. See also * List of rivers of South Dakota This is a list of rivers in the state of South Dakota in the U ...

, the range serves as the eastern border of the southern

. South of Bull Run Creek, the watershed of the range forms the western border of Prince William with Fauquier and thus the eastern slopes are in the former county, while the western slopes are in the latter. The range consists of three closely spaced ridges (with several spurs), which converge in the center of the range. The northern section of the range consists of a solitary ridge, which dies out towards the center of the range, whereupon two ridges to the west gain prominence. In the southern section the central ridge dies out as well and the westernmost ridge solely comprises the range. The section of the Bull Run Mountains south of Thoroughfare Gap is sometimes referred to as the Pond Mountains. The

Broken Hills The Broken Hills, or Broken Hills Range, is a mountain range bordering Churchill County, Nevada Nevada ( ; ) is a U.S. state, state in the Western United States, Western region of the United States. It is bordered by Oregon to the northwest ...

intersect the range south of I-66 in the southern section.

Geology

The Bull Run Mountains are a geological extension of the same formation that makes up the Catoctin Mountain. This formation consist mainly of Catoctin greenstone interspersed with white

quartz Quartz is a hard, crystalline mineral composed of silica (silicon dioxide). The atoms are linked in a continuous framework of SiO4 silicon-oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall chemical form ...

and

Precambrian The Precambrian (or Pre-Cambrian, sometimes abbreviated pꞒ, or Cryptozoic) is the earliest part of Earth's history, set before the current Phanerozoic Eon. The Precambrian is so named because it preceded the Cambrian, the first period of the ...

metamorphosed

basalt Basalt (; ) is an aphanite, aphanitic (fine-grained) extrusive igneous rock formed from the rapid cooling of low-viscosity lava rich in magnesium and iron (mafic lava) exposed at or very near the planetary surface, surface of a terrestrial ...

flows. The lower ridges on the eastern front also contain

Jurassic The Jurassic ( ) is a Geological period, geologic period and System (stratigraphy), stratigraphic system that spanned from the end of the Triassic Period million years ago (Mya) to the beginning of the Cretaceous Period, approximately Mya. The J ...

basalt flows. These rocks were transported westward to their current location and uplifted during the

Alleghenian Orogeny The Alleghanian orogeny or Appalachian orogeny is one of the geological mountain-forming events that formed the Appalachian Mountains and Allegheny Mountains. The term and spelling Alleghany orogeny was originally proposed by H.P. Woodward in 195 ...

History

The

Battle of Thoroughfare Gap The Battle of Thoroughfare Gap, also known as Chapman's Mill, took place on August 28, 1862, in Fauquier County and Prince William County, Virginia, as part of the Northern Virginia Campaign of the American Civil War. Confederate forces under Ma ...

was fought on the mountain prior to the

Second Battle of Manassas The Second Battle of Bull Run or Battle of Second Manassas was fought August 28–30, 1862, in Prince William County, Virginia, as part of the American Civil War. It was the culmination of the Northern Virginia Campaign waged by Confederate ...

during the

American Civil War The American Civil War (April 12, 1861 – May 26, 1865; also known by other names) was a civil war in the United States. It was fought between the Union ("the North") and the Confederacy ("the South"), the latter formed by states th ...

Peaks and gaps

*Peaks (from north to south) **Aldie Mountain [] **Long Hill Mountain [] **Bull Run Ridge [] **High Acre Ridge [] **Griffen Mountain [] **Fishback Ridge [] **Signal Mountain [] **High Point Mountain [] **Bisquit Mountain [] **Pond Mountain [] *Gaps (from north to south) **Buchannon Gap [] **Cold Spring Gap [] **Hopewell Gap [] **Thoroughfare Gap []

Notes

External links

Virginia Outdoors Foundation - Bull Run Mountains Natural Area Preserve

Bull Run Mountains Conservancy, Inc. (BRMC)

Prince William Conservation Alliance
{{Mountains of Virginia Mountain ranges of Virginia Blue Ridge Mountains Mountains of Fauquier County, Virginia Mountains of Loudoun County, Virginia Mountains of Prince William County, Virginia Northern Virginia