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82-620: Catoctin Mountain traverses Frederick County , Maryland and extends into northern Loudoun County , Virginia . It rises to its greatest elevation of 1,900 feet (580 m) above sea level just southwest of Cunningham Falls State Park and is transected by gaps at Braddock Heights (Fairview Pass), Point of Rocks on the Potomac River and Clarke's Gap west of Leesburg , as well as several other unnamed passes in Maryland and Virginia. The mountain

164-423: A mantle wedge above the descending slab. The slab releases water vapor and other volatiles as it descends, which further lowers the melting point, further increasing the amount of decompression melting. Each tectonic setting produces basalt with its own distinctive characteristics. The mineralogy of basalt is characterized by a preponderance of calcic plagioclase feldspar and pyroxene . Olivine can also be

246-576: A monument to Francis Scott Key , the National Museum of Civil War Medicine , Monocacy National Battlefield and South Mountain battlefields, and the Schifferstadt Architectural Museum . Frederick County has experienced a rapid increase in population since the 1980s, including that of minority groups. At the 2010 United States Census , there were 233,385 people, 84,800 households and 61,198 families residing in

328-493: A basalt is diagnostic of how and where it erupted—for example, whether into the sea, in an explosive cinder eruption or as creeping pāhoehoe lava flows, the classic image of Hawaiian basalt eruptions. Basalt that erupts under open air (that is, subaerially ) forms three distinct types of lava or volcanic deposits: scoria ; ash or cinder ( breccia ); and lava flows. Basalt in the tops of subaerial lava flows and cinder cones will often be highly vesiculated , imparting

410-442: A distinctive pillow shape, through which the hot lava breaks to form another pillow. This "pillow" texture is very common in underwater basaltic flows and is diagnostic of an underwater eruption environment when found in ancient rocks. Pillows typically consist of a fine-grained core with a glassy crust and have radial jointing. The size of individual pillows varies from 10 cm up to several metres. When pāhoehoe lava enters

492-427: A flow can shrink in the vertical dimension without fracturing, it cannot easily accommodate shrinking in the horizontal direction unless cracks form; the extensive fracture network that develops results in the formation of columns . These structures, or basalt prisms , are predominantly hexagonal in cross-section, but polygons with three to twelve or more sides can be observed. The size of the columns depends loosely on

574-465: A high content of plagioclase; these are sometimes described as leucobasalts . It can be difficult to distinguish between lighter-colored basalt and andesite , so field researchers commonly use a rule of thumb for this purpose, classifying it as basalt if it has a color index of 35 or greater. The physical properties of basalt result from its relatively low silica content and typically high iron and magnesium content. The average density of basalt

656-621: A lightweight "frothy" texture to the rock. Basaltic cinders are often red, coloured by oxidized iron from weathered iron-rich minerals such as pyroxene . ʻAʻā types of blocky cinder and breccia flows of thick, viscous basaltic lava are common in Hawaiʻi. Pāhoehoe is a highly fluid, hot form of basalt which tends to form thin aprons of molten lava which fill up hollows and sometimes forms lava lakes . Lava tubes are common features of pāhoehoe eruptions. Basaltic tuff or pyroclastic rocks are less common than basaltic lava flows. Usually basalt

738-623: A lower total content of alkali oxides than trachybasalt and most basanites and tephrites. Basalt generally has a composition of 45–52 wt% SiO 2 , 2–5 wt% total alkalis, 0.5–2.0 wt% TiO 2 , 5–14 wt% FeO and 14 wt% or more Al 2 O 3 . Contents of CaO are commonly near 10 wt%, those of MgO commonly in the range 5 to 12 wt%. High-alumina basalts have aluminium contents of 17–19 wt% Al 2 O 3 ; boninites have magnesium (MgO) contents of up to 15 percent. Rare feldspathoid -rich mafic rocks, akin to alkali basalts, may have Na 2 O + K 2 O contents of 12% or more. The abundances of

820-490: A part of Frederick County was combined with a part of Baltimore County to form Carroll County which is east of current day Frederick County. The county has a number of properties on the National Register of Historic Places . According to the U.S. Census Bureau , the county has a total area of 667 square miles (1,730 km ), of which 660 square miles (1,700 km ) is land and 7.2 square miles (19 km ) (1.1%)

902-507: A phenocryst, and when present, may have rims of pigeonite. The groundmass contains interstitial quartz or tridymite or cristobalite . Olivine tholeiitic basalt has augite and orthopyroxene or pigeonite with abundant olivine, but olivine may have rims of pyroxene and is unlikely to be present in the groundmass . Alkali basalts typically have mineral assemblages that lack orthopyroxene but contain olivine. Feldspar phenocrysts typically are labradorite to andesine in composition. Augite

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984-498: A population of 222,938 within 662.88 square miles (1,716.9 km ). Frederick City, Brunswick, Mount Airy, Emmitsburg and Thurmont have municipal police departments. Middletown contracts with the Sheriff's Office for its policing. The following table includes the number of incidents reported for each type of offense from 2012 to 2019. The U.S. Census Bureau reported the following data for Frederick County, June 6, 2011. According to

1066-523: A significant constituent. Accessory minerals present in relatively minor amounts include iron oxides and iron-titanium oxides, such as magnetite , ulvöspinel , and ilmenite . Because of the presence of such oxide minerals, basalt can acquire strong magnetic signatures as it cools, and paleomagnetic studies have made extensive use of basalt. In tholeiitic basalt , pyroxene ( augite and orthopyroxene or pigeonite ) and calcium -rich plagioclase are common phenocryst minerals. Olivine may also be

1148-427: Is 2.9 g/cm , compared, for example, to granite ’s typical density of 2.7 g/cm . The viscosity of basaltic magma is relatively low—around 10 to 10 cP —similar to the viscosity of ketchup , but that is still several orders of magnitude higher than the viscosity of water, which is about 1 cP). Basalt is often porphyritic , containing larger crystals ( phenocrysts ) that formed before the extrusion event that brought

1230-401: Is also produced by some subglacial volcanic eruptions. Basalt is the most common volcanic rock type on Earth, making up over 90% of all volcanic rock on the planet. The crustal portions of oceanic tectonic plates are composed predominantly of basalt, produced from upwelling mantle below the ocean ridges . Basalt is also the principal volcanic rock in many oceanic islands , including

1312-417: Is an 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 surface of a rocky planet or moon . More than 90% of all volcanic rock on Earth is basalt. Rapid-cooling, fine-grained basalt is chemically equivalent to slow-cooling, coarse-grained gabbro . The eruption of basalt lava

1394-753: Is considered a key to understanding plate tectonics , its compositions have been much studied. Although MORB compositions are distinctive relative to average compositions of basalts erupted in other environments, they are not uniform. For instance, compositions change with position along the Mid-Atlantic Ridge , and the compositions also define different ranges in different ocean basins. Mid-ocean ridge basalts have been subdivided into varieties such as normal (NMORB) and those slightly more enriched in incompatible elements (EMORB). Isotope ratios of elements such as strontium , neodymium , lead , hafnium , and osmium in basalts have been much studied to learn about

1476-478: Is defined as volcanic rock with a content of between 45% and 52% silica and no more than 5% alkali metal oxides. This places basalt in the B field of the TAS diagram. Such a composition is described as mafic . Basalt is usually dark grey to black in colour, due to a high content of augite or other dark-coloured pyroxene minerals, but can exhibit a wide range of shading. Some basalts are quite light-coloured due to

1558-434: Is handled by a combination career and volunteer service delivery system. The county employs over 450 career firefighters. Volunteers of the 26 volunteer fire and rescue corporations number approximately 300 active operational members. Fire, rescue and emergency medical services, including advanced life support, are handled by career staffing supplemented by volunteers. The county has a Maryland State Police Medevac located at

1640-619: Is much lower in elevation in Virginia, reaching its highest peak just south of the Potomac at Furnace Mountain (891 feet/271 m) and with only one peak above 800 feet (240 m) south of Leesburg. From its northern terminus in Maryland headed south, the range is composed mainly of a single north–south running ridge with periodic low-lying gaps, though it does contain several spur ridges, most notably near its intersection with South Mountain at its northern terminus. Its ridge character continues south of

1722-540: Is no single prominent peak. However, the ridge clearly has two prominent segments, one south of the Potomac River in Virginia and one north of it in Maryland. According to the USGS, variant names of Catoctin Mountain have included Kittochiny Mountains, Kittockton Mountain, Kittocton Mountain, and South Mountain. However, in Maryland, South Mountain and Catoctin Mountain are separate, roughly parallel, mountains. The portion of

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1804-747: Is observed by geologists at about 20 volcanoes per year. Basalt is also an important rock type on other planetary bodies in the Solar System . For example, the bulk of the plains of Venus , which cover ~80% of the surface, are basaltic; the lunar maria are plains of flood-basaltic lava flows ; and basalt is a common rock on the surface of Mars . Molten basalt lava has a low viscosity due to its relatively low silica content (between 45% and 52%), resulting in rapidly moving lava flows that can spread over great areas before cooling and solidifying. Flood basalts are thick sequences of many such flows that can cover hundreds of thousands of square kilometres and constitute

1886-579: Is rich in titanium compared to augite in tholeiitic basalt. Minerals such as alkali feldspar , leucite , nepheline , sodalite , phlogopite mica, and apatite may be present in the groundmass. Basalt has high liquidus and solidus temperatures—values at the Earth's surface are near or above 1200 °C (liquidus) and near or below 1000 °C (solidus); these values are higher than those of other common igneous rocks. The majority of tholeiitic basalts are formed at approximately 50–100 km depth within

1968-402: Is suppressed. Above this depth, submarine eruptions are often explosive, tending to produce pyroclastic rock rather than basalt flows. These eruptions, described as Surtseyan, are characterised by large quantities of steam and gas and the creation of large amounts of pumice . When basalt erupts underwater or flows into the sea, contact with the water quenches the surface and the lava forms

2050-440: Is too hot and fluid to build up sufficient pressure to form explosive lava eruptions but occasionally this will happen by trapping of the lava within the volcanic throat and buildup of volcanic gases . Hawaiʻi's Mauna Loa volcano erupted in this way in the 19th century, as did Mount Tarawera , New Zealand in its violent 1886 eruption. Maar volcanoes are typical of small basalt tuffs, formed by explosive eruption of basalt through

2132-455: Is ultimately derived from Late Latin basaltes , a misspelling of Latin basanites "very hard stone", which was imported from Ancient Greek βασανίτης ( basanites ), from βάσανος ( basanos , " touchstone "). The modern petrological term basalt , describing a particular composition of lava -derived rock, became standard because of its use by Georgius Agricola in 1546, in his work De Natura Fossilium . Agricola applied

2214-624: Is unstable, and the county, like the state more broadly, has lost dairy farms. The Census Bureau recognizes the following census-designated places in the county: The school district for the county is Frederick County Public Schools . A statewide school for the deaf, Maryland School for the Deaf , is in Frederick. Notable people from Frederick County include: Basalt Basalt ( UK : / ˈ b æ s ɔː l t , - əl t / ; US : / b ə ˈ s ɔː l t , ˈ b eɪ s ɔː l t / )

2296-649: Is water. It is the largest county in Maryland in terms of land area. Frederick County straddles the boundary between the Piedmont Plateau Region and the Appalachian Mountains . The county's two prominent ridges, Catoctin Mountain and South Mountain , form an extension of the Blue Ridge . The Middletown Valley lies between them. Attractions in the Frederick area include the Clustered Spires ,

2378-564: The 2010 Maryland gubernatorial and senatorial elections , giving the Republican Ehrlich – Kane ticket 55% to Democrat O'Malley – Brown's 45. Frederick voters also supported Republican Senate challenger Eric Wargotz over incumbent Democratic Senator Barbara Mikulski by a margin of 51–46, even as Mikulski was winning statewide by a landslide 61–37. Despite its conservative reputation, Frederick County voted in favor of Maryland Question 6 , which legalized same-sex marriage in Maryland. In

2460-688: The 2014 gubernatorial race , Republican Larry Hogan won Frederick County strongly with 63 percent of the vote compared to Democrat Anthony Brown 's 35 percent. In the 2018 elections , despite increased support for Hogan , the Democrats experienced significant gains, securing a majority on the County Council and winning District 3B in the House of Delegates . The Senate election also saw incumbent U.S. Senator Ben Cardin win Frederick County with 51.7% of

2542-529: The Clementine mission demonstrate that the lunar maria possess a continuum of titanium concentrations, and that the highest concentrations are the least abundant. Lunar basalts show exotic textures and mineralogy, particularly shock metamorphism , lack of the oxidation typical of terrestrial basalts, and a complete lack of hydration . Most of the Moon 's basalts erupted between about 3 and 3.5 billion years ago, but

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2624-510: The Fowler's toad . The most notable fish that live on the mountain are trout. There are three known trout species in streams in the region, but only one of them is native. Streams and Lakes in Catoctin Park are stocked with the nonnative rainbow trout every year for sport fishing, and they seem to have a self-sustained population in one creek, Owens Creek. The nonnative brown trout population in

2706-487: The Frederick Municipal Airport and is designated "Trooper 3". Trooper 3 handles calls throughout the state, but provides immediate assistance to local police, fire and rescue services. Like the rest of German -influenced Western Maryland , Frederick County was once staunchly Republican , with Lyndon B. Johnson in 1964 being the last Democrat to carry it in a presidential election until Joe Biden carried

2788-544: The Kittoctons , an American Indian tribe or clan which once lived between the mountain and the Potomac River ; a local tradition asserts that Catoctin means "place of many deer" in an Indian language. Catoctin Mountain is perhaps best known as the site of Camp David , a mountain retreat for presidents of the United States. It was first used by President Franklin D. Roosevelt in the 1930s, who called it " Shangri-La ." In

2870-466: The Maryland Department of Business and Economic Development , the following are the principal employers in Frederick County. This list excludes U.S. post offices and state and local governments, but includes public institutions of higher education. Frederick County leads Maryland in milk production; the county's dairy herds account for one-third of the state's total. However, the dairy market

2952-1176: The Paraná Traps in Brazil, the Siberian Traps in Russia , the Karoo flood basalt province in South Africa, and the Columbia River Plateau of Washington and Oregon . Basalt is also prevalent across extensive regions of the Eastern Galilee , Golan , and Bashan in Israel and Syria . Basalt also is common around volcanic arcs, specially those on thin crust . Ancient Precambrian basalts are usually only found in fold and thrust belts, and are often heavily metamorphosed. These are known as greenstone belts , because low-grade metamorphism of basalt produces chlorite , actinolite , epidote and other green minerals. As well as forming large parts of

3034-453: The Senate election also held in 2022, incumbent Democratic Senator Chris Van Hollen won the county 55.3% to 44.6% over Republican Chris Chaffee. The Frederick County Sheriff's Office provides court protection, jail management and morgue operation for the entire county. It provides police patrol and detective services within the unincorporated areas of Frederick County. The entire county entails

3116-520: The hypabyssal and plutonic equivalents of basalt. During the Hadean , Archean , and early Proterozoic eons of Earth's history, the chemistry of erupted magmas was significantly different from what it is today, due to immature crustal and asthenosphere differentiation. The resulting ultramafic volcanic rocks, with silica (SiO 2 ) contents below 45% and high magnesium oxide (MgO) content, are usually classified as komatiites . The word "basalt"

3198-524: The lanthanide or rare-earth elements (REE) can be a useful diagnostic tool to help explain the history of mineral crystallisation as the melt cooled. In particular, the relative abundance of europium compared to the other REE is often markedly higher or lower, and called the europium anomaly . It arises because Eu can substitute for Ca in plagioclase feldspar, unlike any of the other lanthanides, which tend to only form cations . Mid-ocean ridge basalts (MORB) and their intrusive equivalents, gabbros, are

3280-672: The 1950s, President Dwight Eisenhower renamed it Camp David, after his grandson David Eisenhower . The resort is extremely well guarded by the United States Secret Service , and only approved guests of the President are allowed into the retreat. Due to its proximity to Washington, D.C. , and its beautiful mountain scenery, Camp David has proven to be a popular weekend "getaway" for many United States presidents, and approximately one-third of Catoctin Mountain Park can be closed to

3362-437: The 1980s. It borders the southern border of Pennsylvania and the northeastern border of Virginia . Catoctin Mountain Park in the county is the location of Camp David , a U.S. presidential retreat, and Fort Detrick , a U.S. Army base . The namesake of Frederick County and its county seat is unknown, but it was probably either Frederick, Prince of Wales , or Frederick Calvert, 6th Baron Baltimore . Frederick County

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3444-457: The Earth's crust, basalt also occurs in other parts of the Solar System. Basalt commonly erupts on Io (the third largest moon of Jupiter ), and has also formed on the Moon , Mars , Venus , and the asteroid Vesta . The dark areas visible on Earth's moon , the lunar maria , are plains of flood basaltic lava flows. These rocks were sampled both by the crewed American Apollo program and

3526-935: The Emmitsburg Reservoir, Catoctin Mountain Park , Cunningham Falls State Park , the Frederick Municipal Forest, Gambrill State Park , the Chesapeake and Ohio Canal National Historical Park , all in Maryland, and the Morven Park estate in Virginia. The 27 miles (43 km) long Catoctin Trail traverses the northern half of the range. The trail , which is maintained by the Potomac Appalachian Trail Club , starts at Gambrill State Park, which also contains several shorter hiking and mountain biking trails as well as picnic pavilions, and continues north through

3608-441: The Frederick Municipal Forest to Cunningham Falls State Park and Catoctin Mountain Park. Both parks contain many shorter hiking trails and organized campgrounds. The Journey Through Hallowed Ground Byway , a National Scenic Byway , loops and weaves through the northern part of the range. The name of Catoctin Mountain follows the convention of referring to an entire mountainous ridge as a single "mountain" in situations where there

3690-674: The Potomac in northern Loudoun County, losing elevation, until just north of Leesburg, where the range widens into a broad plateau of undulating hills separated by deep stream valleys. The range reaches its widest point north of Goose Creek at nearly three miles. South of the creek the Catoctin vanishes into the Piedmont countryside near the northern terminus of the Bull Run Mountains at Aldie . A number of federal, state, local, and private protected lands are located on Catoctin Mountain including

3772-795: The area is on the decline now that they are no longer being stocked yearly, but they were once plentiful in Big Hunting Creek. Like the rainbow trout, the native brook trout is stocked in Big Hunting Creek, but their population has been monitored in other waterways as well, and they are noted to be prevalent in Owens Creek and Blue Blazes Creek. Other fish that can be found in the area are longnose dace , roseyside dace , blacknose dace , fantail darter , white sucker , cutlips minnow , creek chub , common shiner , American eel , mottled sculpin , and Blue Ridge sculpin . One survey of aquatic insects in Big Hunting Creek found 20 species of stoneflies ,

3854-476: The basalt/andesite field of the QAPF diagram. Basalt is further distinguished from andesite by its silica content of under 52%. It is often not practical to determine the mineral composition of volcanic rocks, due to their very small grain size, in which case geologists instead classify the rocks chemically, with particular emphasis on the total content of alkali metal oxides and silica ( TAS ); in that context, basalt

3936-475: The characteristic igneous rocks formed at mid-ocean ridges. They are tholeiitic basalts particularly low in total alkalis and in incompatible trace elements, and they have relatively flat REE patterns normalized to mantle or chondrite values. In contrast, alkali basalts have normalized patterns highly enriched in the light REE, and with greater abundances of the REE and of other incompatible elements. Because MORB basalt

4018-544: The county in 2020 . The growth of the county with migration from Washington D.C. had begun to narrow the margins starting from 2008, with John McCain only edging out Barack Obama by only 1,157 votes out of over one hundred thousand cast in the 2008 election. Democratic strength is mostly concentrated in the City of Frederick, while the suburban and rural areas of the county lean more Republican. In state-level elections, Republicans in Frederick rebounded to more historical levels in

4100-484: The county. The population density was 353.5 per square mile (136.5/km ). There were 90,136 housing units at an average density of 136.5 per square mile (52.7/km ). The racial make-up of the county was 81.5% white, 8.6% black or African American, 3.8% Asian, 0.3% American Indian, 2.9% from other races and 2.8% from two or more races. The total (all races) of those self-identifying as Hispanic or Latino origin made up 7.3%, and those persons who were white alone made up 77.8% of

4182-447: The crust, forming an apron of mixed basalt and wall rock breccia and a fan of basalt tuff further out from the volcano. Amygdaloidal structure is common in relict vesicles and beautifully crystallized species of zeolites , quartz or calcite are frequently found. During the cooling of a thick lava flow, contractional joints or fractures form. If a flow cools relatively rapidly, significant contraction forces build up. While

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4264-541: The evolution of the Earth's mantle . Isotopic ratios of noble gases , such as He / He, are also of great value: for instance, ratios for basalts range from 6 to 10 for mid-ocean ridge tholeiitic basalt (normalized to atmospheric values), but to 15–24 and more for ocean-island basalts thought to be derived from mantle plumes . Source rocks for the partial melts that produce basaltic magma probably include both peridotite and pyroxenite . The shape, structure and texture of

4346-479: The immediate area, consists of Proterozoic Catoctin metabasaltic greenstone interspersed by metasedimentary white quartz and other phyllites and Precambrian basalt flows. The greenstone was originally formed about 570 million years ago as part of the rifting of the super-continent, Rodinia. The greenstone was later uplifted during the Alleghenian Orogeny and thrust westward, being interspersed with

4428-708: The islands of Hawaiʻi , the Faroe Islands , and Réunion . The eruption of basalt lava is observed by geologists at about 20 volcanoes per year. Basalt is the rock most typical of large igneous provinces . These include continental flood basalts , the most voluminous basalts found on land. Examples of continental flood basalts included the Deccan Traps in India , the Chilcotin Group in British Columbia , Canada ,

4510-444: The lungless salamanders in the area are the northern dusky , eastern mud , seal , mountain dusky , northern two-lined , longtail , northern spring , four-toed , red-backed , slimy , ravine , and northern red . The rest of the known amphibians are frogs and toads. Some noted species are the wood frog , spring peeper , pickerel frog , green frog , bull frog , northern leopard frog , gray treefrog , American toad , and

4592-604: The magma as it decompresses during its approach to the surface; the erupted lava then solidifies before the gases can escape. When vesicles make up a substantial fraction of the volume of the rock, the rock is described as scoria . The term basalt is at times applied to shallow intrusive rocks with a composition typical of basalt, but rocks of this composition with a phaneritic (coarser) groundmass are more properly referred to either as diabase (also called dolerite) or—when they are more coarse-grained (having crystals over 2 mm across)—as gabbro . Diabase and gabbro are thus

4674-416: The magma to the surface, embedded in a finer-grained matrix . These phenocrysts are usually made of augite, olivine , or a calcium-rich plagioclase, which have the highest melting temperatures of any of the minerals that can typically crystallize from the melt, and which are therefore the first to form solid crystals. Basalt often contains vesicles ; they are formed when dissolved gases bubble out of

4756-704: The mantle. Many alkali basalts may be formed at greater depths, perhaps as deep as 150–200 km. The origin of high-alumina basalt continues to be controversial, with disagreement over whether it is a primary melt or derived from other basalt types by fractionation. Relative to most common igneous rocks, basalt compositions are rich in MgO and CaO and low in SiO 2 and the alkali oxides, i.e., Na 2 O + K 2 O , consistent with their TAS classification . Basalt contains more silica than picrobasalt and most basanites and tephrites but less than basaltic andesite . Basalt has

4838-686: The most prevalent being the winter stonefly . Since 2007, the National Capital Region Network (NCRN) Inventory & Monitoring program has monitored birds across 385 forested plots throughout the Catoctin Mountain region. The top ten most prevalent bird species found in the surveys they completed were the red eyed vireo , scarlet tanager , wood thrush , white-breasted nuthatch , American robin , eastern wood pewee , downy woodpecker , blue jay , eastern tufted titmouse , and red-bellied woodpecker . Other, larger, bird species in

4920-406: The most voluminous of all volcanic formations. Basaltic magmas within Earth are thought to originate from the upper mantle . The chemistry of basalts thus provides clues to processes deep in Earth's interior . Basalt is composed mostly of oxides of silicon, iron, magnesium, potassium, aluminum, titanium, and calcium. Geologists classify igneous rock by its mineral content whenever possible;

5002-422: The mountain due to soil type and quality and provide shelter and food to many of the animal species in the area. There is also a declining population of native orchids that have been monitored and surveyed since the 1960s. There are 22 known species of amphibians living on Catoctin Mountain. The salamanders that live in the region fall into three groups: mole salamanders , newts , and lungless salamanders . Among

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5084-410: The oldest samples are 4.2 billion years old, and the youngest flows, based on the age dating method of crater counting , are estimated to have erupted only 1.2 billion years ago. From 1972 to 1985, five Venera and two VEGA landers successfully reached the surface of Venus and carried out geochemical measurements using X-ray fluorescence and gamma-ray analysis. These returned results consistent with

5166-487: The original on February 13, 2020 . Retrieved January 22, 2016 . </ref> On December 1, 2014, Frederick County changed to a "charter home rule government". Voters approved this governmental change at the November 6, 2012, election with 62,469 voting for the transition and 37,368 against. Previously, Frederick County had been governed by a five-member county commission that could only legislate in local matters with

5248-434: The population. 26.3% of the population cited German ancestry , 17.4% Irish , 12.1% English , 7.2% Italian , and 6.3% American . Of the 84,800 households, 37.6% had children under the age of 18 living with them, 57.8% were married couples living together, 10.0% had a female householder with no husband present, 27.8% were non-families, and 22.0% of all households were made up of individuals. The average household size

5330-695: The prior consent of the Maryland General Assembly . Even that authority was limited to areas authorized by the General Assembly, enabling legislation, or public local laws. As a charter county, Frederick County is now governed by a seven-member county council, with five elected from districts and two elected at-large. A popularly elected county executive is responsible for providing direction, supervision, and administrative oversight of all executive departments, agencies, and offices. The council has broad power to act on most local matters. Jan H. Gardner

5412-578: The public on short notice. Frederick County, Maryland Frederick County is a county located in Maryland , United States. As of the 2020 U.S. census , the population was 271,717. The county seat is Frederick . The county is part of the Capital region of the state. Like other outlying sections of the Washington metropolitan area, Frederick County has experienced a rapid population increase since

5494-475: The rate of cooling; very rapid cooling may result in very small (<1 cm diameter) columns, while slow cooling is more likely to produce large columns. The character of submarine basalt eruptions is largely determined by depth of water, since increased pressure restricts the release of volatile gases and results in effusive eruptions. It has been estimated that at depths greater than 500 metres (1,600 ft), explosive activity associated with basaltic magma

5576-429: The region include turkey vultures , broad-winged hawks , red-tailed hawks , coopers hawks , and wild turkeys , who began to move back into their old native habitat on the mountain in the 1960s. There are 14 species of snake, 2 species of turtle, 1 species of lizard, and species of 1 skink living on Catoctin Mountain. Two of the snakes, the copperhead and the timber rattlesnake , are venomous, but elusive, living in

5658-411: The relative volume percentages of quartz (crystalline silica (SiO 2 )), alkali feldspar , plagioclase , and feldspathoid ( QAPF ) are particularly important. An aphanitic (fine-grained) igneous rock is classified as basalt when its QAPF fraction is composed of less than 10% feldspathoid and less than 20% quartz, and plagioclase makes up at least 65% of its feldspar content. This places basalt in

5740-469: The ridge directly west of Frederick, Maryland , is known locally as Braddock Mountain , and is signed as such where Interstate 70 crosses its summit, although the name is not recorded in the federal Geographic Names Information System . (The GNIS does, however, recognize the community of Braddock Heights , which is located there.) The mountain, like much of the Blue Ridge/South Mountain in

5822-595: The robotic Russian Luna program , and are represented among the lunar meteorites . Lunar basalts differ from their Earth counterparts principally in their high iron contents, which typically range from about 17 to 22 wt% FeO. They also possess a wide range of titanium concentrations (present in the mineral ilmenite ), ranging from less than 1 wt% TiO 2 , to about 13 wt.%. Traditionally, lunar basalts have been classified according to their titanium content, with classes being named high-Ti, low-Ti, and very-low-Ti. Nevertheless, global geochemical maps of titanium obtained from

5904-403: The rock at the landing sites being basalts, including both tholeiitic and highly alkaline basalts. The landers are thought to have landed on plains whose radar signature is that of basaltic lava flows. These constitute about 80% of the surface of Venus. Some locations show high reflectivity consistent with unweathered basalt, indicating basaltic volcanism within the last 2.5 million years. Basalt

5986-455: The sea it usually forms pillow basalts. However, when ʻaʻā enters the ocean it forms a littoral cone , a small cone-shaped accumulation of tuffaceous debris formed when the blocky ʻaʻā lava enters the water and explodes from built-up steam. The island of Surtsey in the Atlantic Ocean is a basalt volcano which breached the ocean surface in 1963. The initial phase of Surtsey's eruption

6068-524: The sedimentary rock deposited during the Paleozoic era. Much of the mountain, being shattered rock, is home to large populations of timber rattlesnakes . There are also black bears , turkeys , and deer , as well as vultures and raptors . Catoctin Mountain is home to more than 280 species of animals, including amphibians, fish, arthropods, birds, reptiles, and mammals. There is a diverse array of native trees and shrubs, which vary along different areas of

6150-479: The shattered rock and eating rodents or other small animals. Other snakes in the region include the northern black racer , northern ring neck , black rat snake , hognose , eastern milk , queen snake , northern water snake , brown water snake , green snake , and eastern garter . The other four known reptiles living on the mountain are eastern box turtles , wood turtles , eastern fence lizards , and five-lined skinks . The name Catoctin probably derives from

6232-648: The term "basalt" to the volcanic black rock beneath the Bishop of Meissen's Stolpen castle , believing it to be the same as the "basaniten" described by Pliny the Elder in AD ;77 in Naturalis Historiae . On Earth, most basalt is formed by decompression melting of the mantle . The high pressure in the upper mantle (due to the weight of the overlying rock ) raises the melting point of mantle rock, so that almost all of

6314-580: The upper mantle is solid. However, mantle rock is ductile (the solid rock slowly deforms under high stress). When tectonic forces cause hot mantle rock to creep upwards, pressure on the ascending rock decreases, and this can lower its melting point enough for the rock to partially melt , producing basaltic magma. Decompression melting can occur in a variety of tectonic settings, including in continental rift zones, at mid-ocean ridges , above geological hotspots , and in back-arc basins . Basalt also forms in subduction zones , where mantle rock rises into

6396-451: The vote. After Biden's win in 2020, the trend towards Democrats continued in 2022, as Democrats increased their majority on the County Council by one seat and gubernatorial candidate Wes Moore won the county with over 53% of the vote compared to 43% for Republican and Emmitsburg resident Dan Cox , the first time Frederick County voted for a Democratic gubernatorial candidate since William Donald Schaefer's landslide victory in 1986 . In

6478-566: Was 2.70 and the average family size was 3.17. The median age was 38.6 years. The median household income was $ 81,686 and the median family income was $ 95,036. Males had a median income of $ 62,494 and females $ 46,720. The per capita income was $ 35,172. About 3.2% of families and 4.8% of the population were below the poverty line , including 5.8% of those under age 18 and 5.6% of those age 65 or over.<ref"> "DP03 SELECTED ECONOMIC CHARACTERISTICS – 2006-2010 American Community Survey 5-Year Estimates" . United States Census Bureau. Archived from

6560-517: Was created in 1748 by the Province of Maryland from parts of Prince George's County and Baltimore County . In 1776, following US independence , Frederick County was divided into three parts. The westernmost portion became Washington County , named after George Washington , the southernmost portion became Montgomery County , named after another Revolutionary War general, Richard Montgomery . The northern portion remained Frederick County. In 1837,

6642-420: Was elected the first Frederick County executive in 2014 and was re-elected in 2018. The members of the third Frederick County Council for the term beginning 2022 are: The Frederick County state's attorney, first elected November 2, 2010, and re-elected in 2018 and 2022, is Charlie Smith, a Republican. The sheriff of Frederick County is Republican Chuck Jenkins. Frederick County's fire and rescue service

6724-400: Was highly explosive, as the magma was quite fluid, causing the rock to be blown apart by the boiling steam to form a tuff and cinder cone. This has subsequently moved to a typical pāhoehoe-type behaviour. Volcanic glass may be present, particularly as rinds on rapidly chilled surfaces of lava flows, and is commonly (but not exclusively) associated with underwater eruptions. Pillow basalt

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