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36-863: The Bull Run Mountains are a mountain range of the Blue Ridge Mountains in northern Virginia in the United States . Located approximately 20 miles (32 km) east of the main chain, across the Loudoun Valley . The Bull Run Mountains, together with Catoctin Mountain in Virginia and Maryland , 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

72-407: A byproduct of the thermal cracking of petroleum naphtha or oil, as a side product in the production of ethylene . Where thermal cracking of oil is less common, isopentane can be dehydrogenated or isoprene can be synthesized from isobutylene and formaldehyde . Where cheap acetylene is produced from coal-derived calcium carbide , it may be combined with acetone to make 3-methylbutynol which

108-409: A massive texture and missed the main episode of Mesoproterozoic compression. At the time of their emergence, the Blue Ridge were among the highest mountains in the world and reached heights comparable to the much younger Alps . Weathering , erosion , and mass wasting over hundreds of millions of years has resulted in much shorter peaks. At the foot of the Blue Ridge, various tribes including

144-422: A professor and geologist at George Washington University , provide greater insight into the petrologic and geochronologic history of the Blue Ridge basement suites. Modern studies have found that the basement geology of the Blue Ridge is made of compositionally unique gneisses and granitoids , including orthopyroxene-bearing charnockites. Analysis of zircon minerals in the granite completed by John Aleinikoff at

180-570: 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 , the John Marshall Highway ( Virginia Route 55 ) and

216-422: Is about equivalent to methane emissions and accounts for around one-third of all hydrocarbons released into the atmosphere. In deciduous forests, isoprene makes up approximately 80% of hydrocarbon emissions. While their contribution is small compared to trees, microscopic and macroscopic algae also produce isoprene. Isoprene is made through the methyl-erythritol 4-phosphate pathway (MEP pathway, also called

252-765: Is incorporated into and helps stabilize cell membranes in response to heat stress. Isoprene also confers resistance to reactive oxygen species. The amount of isoprene released from isoprene-emitting vegetation depends on leaf mass, leaf area, light (particularly photosynthetic photon flux density, or PPFD) and leaf temperature. Thus, during the night, little isoprene is emitted from tree leaves, whereas daytime emissions are expected to be substantial during hot and sunny days, up to 25 μg/(g dry-leaf-weight)/hour in many oak species. The isoprene skeleton can be found in naturally occurring compounds called terpenes and terpenoid (oxygenated terpenes), collectively called isoprenoids. These compounds do not arise from isoprene itself. Instead,

288-436: Is regulated both by substrate level and enzyme activity. Isoprene is the most abundant hydrocarbon measurable in the breath of humans. The estimated production rate of isoprene in the human body is 0.15 μmol /(kg·h), equivalent to approximately 17 mg/day for a person weighing 70 kg. Human breath isoprene originates from lipolytic cholesterol metabolism within the skeletal muscular peroxisomes and IDI2 gene acts as

324-548: Is then hydrogenated and dehydrated to isoprene. About 800,000 metric tons are produced annually. About 95% of isoprene production is used to produce cis-1,4-polyisoprene—a synthetic version of natural rubber . Natural rubber consists mainly of poly-cis-isoprene with a molecular mass of 100,000 to 1,000,000 g/mol. Typically natural rubber contains a few percent of other materials, such as proteins, fatty acids, resins, and inorganic materials. Some natural rubber sources, called gutta percha , are composed of trans-1,4-polyisoprene,

360-624: The Manassas Gap Railroad pass through the range at Thoroughfare Gap . The range extends in a southwest–northeast orientation for approximately 15 miles (24 km) from Aldie in Loudoun County , through western Prince William County to New Baltimore in Fauquier County . In the north, from Aldie to the headwaters of Bull Run Creek , the range serves as the eastern border of the southern Loudoun Valley . South of Bull Run Creek,

396-478: The New York–New Jersey Highlands . The petrologic and geochronologic data suggest that the Blue Ridge basement is a composite orogenic crust that was emplaced during several episodes from a crustal magma source. Field relationships further illustrate that rocks emplaced prior to 1.078–1.064 billion years ago preserve deformational features. Those emplaced post-1.064 billion years ago generally have

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432-694: The Roanoke River gap. To the west of the Blue Ridge, between it and the bulk of the Appalachians, lies the Great Appalachian Valley , bordered on the west by the Ridge and Valley province of the Appalachian range. The Blue Ridge Mountains are known for having a bluish color when seen from a distance. Trees put the "blue" in Blue Ridge, from the isoprene released into the atmosphere. This contributes to

468-729: The Siouan Manahoacs , the Iroquois , and the Shawnee hunted and fished. A German physician-explorer, John Lederer , first reached the crest of the Blue Ridge in 1669 and again the following year; he also recorded the Virginia Siouan name for the Blue Ridge ( Ahkonshuck ). At the Treaty of Albany negotiated by Virginia Lieutenant Governor Alexander Spotswood with the Iroquois between 1718 and 1722,

504-499: The U.S. Geological Survey has provided more detailed emplacement ages. Many of the features found in the Blue Ridge and documented by Tollo and others have confirmed that the rocks exhibit many similar features in other North American Grenville-age terranes . The lack of a calc-alkaline affinity and zircon ages less than 1.2 billion years old suggest that the Blue Ridge is distinct from the Adirondacks , Green Mountains, and possibly

540-530: The pyrolysis of natural rubber. He correctly deduced the mass shares of carbon and hydrogen (but due to modern atomic weight of carbon not yet adopted at the Karlsruhe Congress arrived at an incorrect formula C 10 H 8 ). He didn't specify the reasons for the name, but it's hypothesized that it came from "propylene" with which isoprene shares some physical and chemical properties. The first one to observe recombination of isoprene into rubber-like substance

576-665: The Blue Ridge Mountains is Roanoke , located in Southwest Virginia , while the largest Metropolitan Statistical Area is the Greenville metropolitan area in Upstate, South Carolina . Other notable cities in the Blue Ridge Mountains include Charlottesville , Frederick , Hagerstown , Chambersburg , Asheville , Johnson City , and Lynchburg . Isoprene C. G. Williams named the compound in 1860 after obtaining it from

612-691: The Blue Ridge: the Brushy Mountains and the South Mountains . In Virginia the Southwest Mountains are an anticlinal range that similarly parallels the Blue Ridge. The Blue Ridge extends as far south as Mount Oglethorpe in Georgia and as far north into Pennsylvania as South Mountain . While South Mountain dwindles to hills between Gettysburg and Harrisburg , the band of ancient rocks that form

648-684: The Iroquois ceded lands they had conquered south of the Potomac River and east of the Blue Ridge to the Virginia Colony . This treaty made the Blue Ridge the new demarcation point between the areas and tribes subject to the Six Nations, and those tributaries to the colony. When colonists began to disregard this by crossing the Blue Ridge and settling in the Shenandoah Valley in the 1730s, the Iroquois began to object, finally selling their rights to

684-400: The cell membrane monolayer of many Archaea , filling the space between the diglycerol tetraether head groups. This is thought to add structural resistance to harsh environments in which many Archaea are found. Similarly, natural rubber is composed of linear polyisoprene chains of very high molecular weight and other natural molecules. Isoprene is most readily available industrially as

720-758: The characteristic haze on the mountains and their perceived color. Within the Blue Ridge province are two major national parks: the Shenandoah National Park in the northern section and the Great Smoky Mountains National Park in the southern section. The Blue Ridge Parkway , a 469-mile (755 km) long scenic highway, connects the two parks and runs along the ridge crest-lines, as does the Appalachian Trail . Eight national forests include George Washington and Jefferson , Cherokee , Pisgah , Nantahala and Chattahoochee . Although

756-613: The core of the Blue Ridge continues northeast through the New Jersey and Hudson River highlands, eventually reaching the Berkshires of Massachusetts and the Green Mountains of Vermont . The Blue Ridge contains the highest mountains in eastern North America south of Baffin Island . About 125 peaks exceed 5,000 feet (1,500 m) in elevation. The highest peak in the Blue Ridge (and in

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792-600: The entire Appalachian chain) is Mount Mitchell in North Carolina at 6,684 feet (2,037 m). There are 39 peaks in North Carolina and Tennessee higher than 6,000 feet (1,800 m); by comparison, in the northern portion of the Appalachian chain only New Hampshire 's Mount Washington rises above 6,000 feet (1,800 m). Southern Sixers is a term used by peak baggers for this group of mountains. The Blue Ridge Parkway runs 469 miles (755 km) along crests of

828-626: The hypothesis that isoprene may protect plants against heat stress (thermotolerance hypothesis, see below). Emission of isoprene is also observed in some bacteria and this is thought to come from non-enzymatic degradations from DMAPP. Global emission of isoprene by plants is estimated at 350 million tons per year. Isoprene emission in plants is controlled both by the availability of the substrate (DMAPP) and by enzyme (isoprene synthase) activity. In particular, light, CO 2 and O 2 dependencies of isoprene emission are controlled by substrate availability, whereas temperature dependency of isoprene emission

864-485: The non- mevalonate pathway ) in the chloroplasts of plants. One of the two end-products of MEP pathway, dimethylallyl pyrophosphate (DMAPP), is cleaved by the enzyme isoprene synthase to form isoprene and diphosphate. Therefore, inhibitors that block the MEP pathway, such as fosmidomycin , also block isoprene formation. Isoprene emission increases dramatically with temperature and maximizes at around 40 °C. This has led to

900-409: The precursor to isoprene units in biological systems is dimethylallyl pyrophosphate (DMAPP) and its isomer isopentenyl pyrophosphate (IPP). The plural 'isoprenes' is sometimes used to refer to terpenes in general. Examples of isoprenoids include carotene , phytol , retinol ( vitamin A ), tocopherol ( vitamin E ), dolichols , and squalene . Heme A has an isoprenoid tail, and lanosterol ,

936-601: The production determinant. Due to the absence of IDI2 gene, animals such as pigs and bottle-nose dolphins do not exhale isoprene. Isoprene is common in low concentrations in many foods. Many species of soil and marine bacteria, such as Actinomycetota , are capable of degrading isoprene and using it as a fuel source. Isoprene emission appears to be a mechanism that trees use to combat abiotic stresses . In particular, isoprene has been shown to protect against moderate heat stress (around 40 °C). It may also protect plants against large fluctuations in leaf temperature. Isoprene

972-456: The range lacks the tree line found at lower elevations in the northern half of the Appalachian range. Statistical modelling predicts that the alpine tree line would exist at above 7,985 feet (2434 m) in the climate zone and latitude of the southern Appalachians. The highest parts of the Blue Ridge are generally vegetated in dense Southern Appalachian spruce-fir forests . The area is host to many animals, including: The largest city located in

1008-538: 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 intersect the range south of I-66 in the southern section. The Bull Run Mountains are a geological extension of

1044-586: The same formation that makes up the Catoctin Mountain. This formation consist mainly of Catoctin greenstone interspersed with white quartz and Precambrian metamorphosed basalt flows. The lower ridges on the eastern front also contain Jurassic basalt flows. These rocks were transported westward to their current location and uplifted during the Alleghenian Orogeny . The Battle of Thoroughfare Gap

1080-490: The southern Appalachians and links two national parks: Shenandoah and Great Smoky Mountains . In many places along the parkway, there are metamorphic rocks ( gneiss ) with folded bands of light-and dark-colored minerals, which sometimes look like the folds and swirls in a marble cake. Most of the rocks that form the Blue Ridge Mountains are ancient granitic charnockites , metamorphosed volcanic formations, and sedimentary limestone. Recent studies completed by Richard Tollo,

1116-474: The sterol precursor in animals, is derived from squalene and hence from isoprene. The functional isoprene units in biological systems are dimethylallyl pyrophosphate (DMAPP) and its isomer isopentenyl pyrophosphate (IPP), which are used in the biosynthesis of naturally occurring isoprenoids such as carotenoids , quinones , lanosterol derivatives (e.g. steroids) and the prenyl chains of certain compounds (e.g. phytol chain of chlorophyll). Isoprenes are used in

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1152-740: The term "Blue Ridge" is sometimes applied exclusively to the eastern edge or front range of the Appalachian Mountains, the geological definition of the Blue Ridge province extends westward to the Ridge and Valley area, encompassing the Great Smoky Mountains , the Great Balsams , the Roans , the Blacks , and other mountain ranges. In North Carolina, two lower elevation ranges to the east, referred to as foothills , are also often included as "spurs" of

1188-455: The valley, on the west side of the Blue Ridge, at the Treaty of Lancaster in 1744. The Blue Ridge Mountains have stunted oak and oak-hickory forest habitats , which comprise most of the Appalachian slope forests. Flora also includes grass, shrubs, hemlock and mixed-oak pine forests. While the Blue Ridge range includes the highest summits in the eastern United States, the climate is nevertheless too warm to support an alpine zone , and thus

1224-399: 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

1260-431: Was Gustave Bouchardat  [ de ] in 1879, and William A. Tilden identified its structure five years later. Isoprene is produced and emitted by many species of trees (major producers are oaks , poplars , eucalyptus , and some legumes). Yearly production of isoprene emissions by vegetation is around 600 million metric tons , half from tropical broadleaf trees and the remainder primarily from shrubs . This

1296-738: Was fought on the mountain prior to the Second Battle of Manassas during the American Civil War . Blue Ridge Mountains The Blue Ridge Mountains are a physiographic province of the larger Appalachian Highlands range. The mountain range is located in the Eastern United States and extends 550 miles southwest from southern Pennsylvania through Maryland , West Virginia , Virginia , North Carolina , South Carolina , Tennessee , and Georgia . The province consists of northern and southern physiographic regions, which divide near

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