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72-489: Saunders Basin ( 76°50′S 155°0′W  /  76.833°S 155.000°W  / -76.833; -155.000 ) is an undersea basin in the central Ross shelf named in association with Saunders Coast. Name approved 6/88 (ACUF 228). [REDACTED]  This article incorporates public domain material from "Saunders Coast" . Geographic Names Information System . United States Geological Survey .   [REDACTED] This Ross Dependency location article

144-495: A "Concise" subset of the NGNDB that listed "major features", and a "Historical" subset that included the features that no longer exist. There is no differentiation amongst different types of populated places. In the words of the aforementioned 1986 USACE report, "[a] subdivision having one inhabitant is as significant as a major metropolitan center such as New York City ". In comparing GNIS populated place records with data from

216-588: A 1962 replacement of the "Nigger" racial pejorative for African Americans with "Negro" and a 1974 replacement of the "Jap" racial pejorative for Japanese Americans with "Japanese". In 2015, a cross-reference of the GNIS database against the Racial Slur Database had found 1441 racial slur placenames, every state of the United States having them, with California having 159 and the state with

288-694: A 2008 book on ethnic slurs in U.S. placenames Mark Monmonier of Syracuse University discovered "Niger Hill" in Potter County, Pennsylvania , an erroneous transcription of "Nigger Hill" from a 1938 map, and persuaded the USBGN to change it to "Negro Hill". In November 2021, the United States Secretary of the Interior issued an order instructing that "Squaw" be removed from usage by the U.S. federal government. Prior efforts had included

360-419: A continued supply of lava and its pressure on a solidified crust. Most basaltic lavas are of ʻaʻā or pāhoehoe types, rather than block lavas. Underwater, they can form pillow lavas , which are rather similar to entrail-type pahoehoe lavas on land. Ultramafic lavas, such as komatiite and highly magnesian magmas that form boninite , take the composition and temperatures of eruptions to the extreme. All have

432-455: A darker groundmass , including amphibole or pyroxene phenocrysts. Mafic or basaltic lavas are typified by relatively high magnesium oxide and iron oxide content (whose molecular formulas provide the consonants in mafic) and have a silica content limited to a range of 52% to 45%. They generally erupt at temperatures of 1,100 to 1,200 °C (2,010 to 2,190 °F) and at relatively low viscosities, around 10 to 10 cP (10 to 100 Pa⋅s). This

504-420: A dome forms on an inclined surface it can flow in short thick flows called coulées (dome flows). These flows often travel only a few kilometres from the vent. Lava tubes are formed when a flow of relatively fluid lava cools on the upper surface sufficiently to form a crust. Beneath this crust, which being made of rock is an excellent insulator, the lava can continue to flow as a liquid. When this flow occurs over

576-422: A later phase). Generic designations were given after specific names, so (for examples) Mount Saint Helens was recorded as "Saint Helens, Mount", although cities named Mount Olive , not actually being mountains, would not take "Mount" to be a generic part and would retain their order "Mount Olive". The primary geographic coordinates of features which occupy an area, rather than being a single point feature, were

648-465: A massive dense core, which is the most active part of the flow. As pasty lava in the core travels downslope, the clinkers are carried along at the surface. At the leading edge of an ʻaʻā flow, however, these cooled fragments tumble down the steep front and are buried by the advancing flow. This produces a layer of lava fragments both at the bottom and top of an ʻaʻā flow. Accretionary lava balls as large as 3 metres (10 feet) are common on ʻaʻā flows. ʻAʻā

720-794: A precursor pilot project run over the states of Kansas and Colorado in 1976, and produced 5 databases. It excluded several classes of feature because they were better documented in non-USGS maps, including airports, the broadcasting masts for radio and television stations, civil divisions, regional and historic names, individual buildings, roads, and triangulation station names. The databases were initially available on paper (2 to 3 spiral-bound volumes per state), on microfiche , and on magnetic tape encoded (unless otherwise requested) in EBCDIC with 248-byte fixed-length records in 4960-byte blocks . The feature classes for association with each name included (for examples) "locale" (a "place at which there

792-412: A second Alaska file) data from the 1:100000 and 1:250000 scale USGS maps. Map names were recorded exactly as on the maps themselves, with the exceptions for diacritics as with the NGNDB. Unlike the NGNDB, locations were the geographic coördinates of the south-east corner of the given map, except for American Samoa and Guam maps where they were of the north-east cornder. The TMNDB was later renamed

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864-960: A silica content greater than 63%. They include rhyolite and dacite lavas. With such a high silica content, these lavas are extremely viscous, ranging from 10 cP (10 Pa⋅s) for hot rhyolite lava at 1,200 °C (2,190 °F) to 10 cP (10 Pa⋅s) for cool rhyolite lava at 800 °C (1,470 °F). For comparison, water has a viscosity of about 1 cP (0.001 Pa⋅s). Because of this very high viscosity, felsic lavas usually erupt explosively to produce pyroclastic (fragmental) deposits. However, rhyolite lavas occasionally erupt effusively to form lava spines , lava domes or "coulees" (which are thick, short lava flows). The lavas typically fragment as they extrude, producing block lava flows. These often contain obsidian . Felsic magmas can erupt at temperatures as low as 800 °C (1,470 °F). Unusually hot (>950 °C; >1,740 °F) rhyolite lavas, however, may flow for distances of many tens of kilometres, such as in

936-450: A silica content under 45%. Komatiites contain over 18% magnesium oxide and are thought to have erupted at temperatures of 1,600 °C (2,910 °F). At this temperature there is practically no polymerization of the mineral compounds, creating a highly mobile liquid. Viscosities of komatiite magmas are thought to have been as low as 100 to 1000 cP (0.1 to 1 Pa⋅s), similar to that of light motor oil. Most ultramafic lavas are no younger than

1008-441: A similar manner to ʻaʻā flows but their more viscous nature causes the surface to be covered in smooth-sided angular fragments (blocks) of solidified lava instead of clinkers. As with ʻaʻā flows, the molten interior of the flow, which is kept insulated by the solidified blocky surface, advances over the rubble that falls off the flow front. They also move much more slowly downhill and are thicker in depth than ʻaʻā flows. Pillow lava

1080-530: A solid crust that insulates the remaining liquid lava, helping to keep it hot and inviscid enough to continue flowing. The word lava comes from Italian and is probably derived from the Latin word labes , which means a fall or slide. An early use of the word in connection with extrusion of magma from below the surface is found in a short account of the 1737 eruption of Vesuvius , written by Francesco Serao , who described "a flow of fiery lava" as an analogy to

1152-575: A temperature of 1,100 to 1,200 °C (2,010 to 2,190 °F). On the Earth, most lava flows are less than 10 km (6.2 mi) long, but some pāhoehoe flows are more than 50 km (31 mi) long. Some flood basalt flows in the geologic record extend for hundreds of kilometres. The rounded texture makes pāhoehoe a poor radar reflector, and is difficult to see from an orbiting satellite (dark on Magellan picture). Block lava flows are typical of andesitic lavas from stratovolcanoes. They behave in

1224-501: A volcano extrudes silicic lava, it can form an inflation dome or endogenous dome , gradually building up a large, pillow-like structure which cracks, fissures, and may release cooled chunks of rock and rubble. The top and side margins of an inflating lava dome tend to be covered in fragments of rock, breccia and ash. Examples of lava dome eruptions include the Novarupta dome, and successive lava domes of Mount St Helens . When

1296-473: Is a stub . You can help Misplaced Pages by expanding it . This Marie Byrd Land location article is a stub . You can help Misplaced Pages by expanding it . Geographic Names Information System The Geographic Names Information System ( GNIS ) is a database of name and location information about more than two million physical and cultural features throughout the United States and its territories;

1368-402: Is a large subsidence crater, can form in a stratovolcano, if the magma chamber is partially or wholly emptied by large explosive eruptions; the summit cone no longer supports itself and thus collapses in on itself afterwards. Such features may include volcanic crater lakes and lava domes after the event. However, calderas can also form by non-explosive means such as gradual magma subsidence. This

1440-456: Is also often called lava . A lava flow is an outpouring of lava during an effusive eruption . (An explosive eruption , by contrast, produces a mixture of volcanic ash and other fragments called tephra , not lava flows.) The viscosity of most lava is about that of ketchup , roughly 10,000 to 100,000 times that of water. Even so, lava can flow great distances before cooling causes it to solidify, because lava exposed to air quickly develops

1512-415: Is basaltic lava that has a smooth, billowy, undulating, or ropy surface. These surface features are due to the movement of very fluid lava under a congealing surface crust. The Hawaiian word was introduced as a technical term in geology by Clarence Dutton . A pāhoehoe flow typically advances as a series of small lobes and toes that continually break out from a cooled crust. It also forms lava tubes where

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1584-719: Is concentrated in a thin layer in the toothpaste next to the tube and only there does the toothpaste behave as a fluid. Thixotropic behavior also hinders crystals from settling out of the lava. Once the crystal content reaches about 60%, the lava ceases to behave like a fluid and begins to behave like a solid. Such a mixture of crystals with melted rock is sometimes described as crystal mush . Lava flow speeds vary based primarily on viscosity and slope. In general, lava flows slowly, with typical speeds for Hawaiian basaltic flows of 0.40 km/h (0.25 mph) and maximum speeds of 10 to 48 km/h (6 to 30 mph) on steep slopes. An exceptional speed of 32 to 97 km/h (20 to 60 mph)

1656-546: Is mostly determined by composition but also depends on temperature and shear rate. Lava viscosity determines the kind of volcanic activity that takes place when the lava is erupted. The greater the viscosity, the greater the tendency for eruptions to be explosive rather than effusive. As a result, most lava flows on Earth, Mars, and Venus are composed of basalt lava. On Earth, 90% of lava flows are mafic or ultramafic, with intermediate lava making up 8% of flows and felsic lava making up just 2% of flows. Viscosity also determines

1728-444: Is one of three basic types of flow lava. ʻAʻā is basaltic lava characterized by a rough or rubbly surface composed of broken lava blocks called clinker. The word is Hawaiian meaning "stony rough lava", but also to "burn" or "blaze"; it was introduced as a technical term in geology by Clarence Dutton . The loose, broken, and sharp, spiny surface of an ʻaʻā flow makes hiking difficult and slow. The clinkery surface actually covers

1800-443: Is or was human activity" not covered by a more specific feature class), "populated place" (a "place or area with clustered or scattered buildings"), "spring" (a spring ), "lava" (a lava flow , kepula , or other such feature), and "well" (a well ). Mountain features would fall into "ridge", "range", or "summit" classes. A feature class "tank" was sometimes used for lakes, which was problematic in several ways. This feature class

1872-474: Is similar to the viscosity of ketchup , although it is still many orders of magnitude higher than that of water. Mafic lavas tend to produce low-profile shield volcanoes or flood basalts , because the less viscous lava can flow for long distances from the vent. The thickness of a solidified basaltic lava flow, particularly on a low slope, may be much greater than the thickness of the moving molten lava flow at any one time, because basaltic lavas may "inflate" by

1944-454: Is the lava structure typically formed when lava emerges from an underwater volcanic vent or subglacial volcano or a lava flow enters the ocean. The viscous lava gains a solid crust on contact with the water, and this crust cracks and oozes additional large blobs or "pillows" as more lava emerges from the advancing flow. Since water covers the majority of Earth 's surface and most volcanoes are situated near or under bodies of water, pillow lava

2016-422: Is typical of many shield volcanoes. Cinder cones and spatter cones are small-scale features formed by lava accumulation around a small vent on a volcanic edifice. Cinder cones are formed from tephra or ash and tuff which is thrown from an explosive vent. Spatter cones are formed by accumulation of molten volcanic slag and cinders ejected in a more liquid form. Another Hawaiian English term derived from

2088-516: Is usually of higher viscosity than pāhoehoe. Pāhoehoe can turn into ʻaʻā if it becomes turbulent from meeting impediments or steep slopes. The sharp, angled texture makes ʻaʻā a strong radar reflector, and can easily be seen from an orbiting satellite (bright on Magellan pictures). ʻAʻā lavas typically erupt at temperatures of 1,050 to 1,150 °C (1,920 to 2,100 °F) or greater. Pāhoehoe (also spelled pahoehoe , from Hawaiian [paːˈhoweˈhowe] meaning "smooth, unbroken lava")

2160-646: Is very common. Because it is formed from viscous molten rock, lava flows and eruptions create distinctive formations, landforms and topographical features from the macroscopic to the microscopic. Volcanoes are the primary landforms built by repeated eruptions of lava and ash over time. They range in shape from shield volcanoes with broad, shallow slopes formed from predominantly effusive eruptions of relatively fluid basaltic lava flows, to steeply-sided stratovolcanoes (also known as composite volcanoes) made of alternating layers of ash and more viscous lava flows typical of intermediate and felsic lavas. A caldera , which

2232-561: The Geographic Cell Names database (GCNDB hereafter) in the 1990s. The Generic database was in essence a machine-readable glossary of terms and abbreviations taken from the map sources, with their definitions, grouped into collections of related terms. The National Atlas database was an abridged version of the NGNDB that contained only those entries that were in the index to the USGS National Atlas of

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2304-494: The Hawaiian language , a kīpuka denotes an elevated area such as a hill, ridge or old lava dome inside or downslope from an area of active volcanism. New lava flows will cover the surrounding land, isolating the kīpuka so that it appears as a (usually) forested island in a barren lava flow. Lava domes are formed by the extrusion of viscous felsic magma. They can form prominent rounded protuberances, such as at Valles Caldera . As

2376-889: The Proterozoic , with a few ultramafic magmas known from the Phanerozoic in Central America that are attributed to a hot mantle plume . No modern komatiite lavas are known, as the Earth's mantle has cooled too much to produce highly magnesian magmas. Some silicate lavas have an elevated content of alkali metal oxides (sodium and potassium), particularly in regions of continental rifting , areas overlying deeply subducted plates , or at intraplate hotspots . Their silica content can range from ultramafic ( nephelinites , basanites and tephrites ) to felsic ( trachytes ). They are more likely to be generated at greater depths in

2448-520: The Snake River Plain of the northwestern United States. Intermediate or andesitic lavas contain 52% to 63% silica, and are lower in aluminium and usually somewhat richer in magnesium and iron than felsic lavas. Intermediate lavas form andesite domes and block lavas and may occur on steep composite volcanoes , such as in the Andes . They are also commonly hotter than felsic lavas, in

2520-714: The Thematic Mapper of the Landsat program , researchers from the University of Connecticut in 2001 discovered that "a significant number" of populated places in Connecticut had no identifiable human settlement in the land use data and were at road intersections. They found that such populated places with no actual settlement often had "Corner" in their names, and hypothesized that either these were historical records or were "cartographic locators". In surveying in

2592-710: The associated states of the Marshall Islands , Federated States of Micronesia , and Palau ; and Antarctica . It is a type of gazetteer . It was developed by the United States Geological Survey (USGS) in cooperation with the United States Board on Geographic Names (BGN) to promote the standardization of feature names. Data were collected in two phases. Although a third phase was considered, which would have handled name changes where local usages differed from maps, it

2664-418: The most abundant elements of the Earth's crust , with smaller quantities of aluminium , calcium , magnesium , iron , sodium , and potassium and minor amounts of many other elements. Petrologists routinely express the composition of a silicate lava in terms of the weight or molar mass fraction of the oxides of the major elements (other than oxygen) present in the lava. The silica component dominates

2736-548: The 1990s (still including tape and paper) to floppy disc , over FTP , and on CD-ROM . The CD-ROM edition only included the NGNDB, the AGNDB, the GCNDB, and a bibliographic reference database (RDB); but came with database search software that ran on PC DOS (or compatible) version 3.0 or later. The FTP site included extra topical databases: a subset of the NGNDB that only included the records with feature classes for populated places,

2808-572: The GNIS web site and can review the justifications and supporters of the proposals. The usual sources of name change requests are an individual state's board on geographic names, or a county board of governors. This does not always succeed, the State Library of Montana having submitted three large sets of name changes that have not been incorporated into the GNIS database. Conversely, a group of middle school students in Alaska succeeded, with

2880-466: The United States , with the coördinates published in the latter substituted for the coördinates from the former. The Board on Geographic Names database was a record of investigative work of the USGS Board on Geographic Names ' Domestic Names Committee, and decisions that it had made from 1890 onwards, as well as names that were enshrined by Acts of Congress . Elevation and location data followed

2952-905: The United States, a "Corner" is a corner of the surveyed polygon enclosing an area of land, whose location is, or was (since corners can become "lost" or "obliterated" ), marked in various ways including with trees known as "bearing trees" ("witness trees" in older terminology ) or "corner monuments". From analysing Native American names in the database in order to compile a dictionary, professor William Bright of UCLA observed in 2004 that some GNIS entries are "erroneous; or refer to long-vanished railroad sidings where no one ever lived". Such false classifications have propagated to other geographical information sources, such as incorrectly classified train stations appearing as towns or neighborhoods on Google Maps. The GNIS accepts proposals for new or changed names for U.S. geographical features through The National Map Corps . The general public can make proposals at

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3024-989: The aspect (thickness relative to lateral extent) of flows, the speed with which flows move, and the surface character of the flows. When highly viscous lavas erupt effusively rather than in their more common explosive form, they almost always erupt as high-aspect flows or domes. These flows take the form of block lava rather than ʻaʻā or pāhoehoe. Obsidian flows are common. Intermediate lavas tend to form steep stratovolcanoes, with alternating beds of lava from effusive eruptions and tephra from explosive eruptions. Mafic lavas form relatively thin flows that can move great distances, forming shield volcanoes with gentle slopes. In addition to melted rock, most lavas contain solid crystals of various minerals, fragments of exotic rocks known as xenoliths , and fragments of previously solidified lava. The crystal content of most lavas gives them thixotropic and shear thinning properties. In other words, most lavas do not behave like Newtonian fluids, in which

3096-426: The coordinates were taken to be those of a primary civic feature such as the city hall or town hall , main public library , main highway intersection, main post office, or central business district regardless of changes over time; these coordinates are called the "primary point". Secondary coordinates were only an aid to locating which topographic map(s) the feature extended across, and were "simply anywhere on

3168-424: The entire United States and that were abridged versions of the data in the other 57: one for the 50,000 most well known populated places and features, and one for most of the populated places. The files were compiled from all of the names to be found on USGS topographic maps, plus data from various state map sources. In phase 1, elevations were recorded in feet only, with no conversion to metric, and only if there

3240-418: The eruption. A cooling lava flow shrinks, and this fractures the flow. Basalt flows show a characteristic pattern of fractures. The uppermost parts of the flow show irregular downward-splaying fractures, while the lower part of the flow shows a very regular pattern of fractures that break the flow into five- or six-sided columns. The irregular upper part of the solidified flow is called the entablature , while

3312-423: The feature and on the topographic map with which it is associated". River sources were determined by the shortest drain, subject to the proximities of other features that were clearly related to the river by their names. The USGS Topographic Map Names database (TMNDB hereafter) was also 57 computer files containing the names of maps: 56 for 1:24000 scale USGS maps as with the NGNDB, the 57th being (rather than

3384-654: The flood basalts of South America formed in this manner. Flood basalts typically crystallize little before they cease flowing, and, as a result, flow textures are uncommon in less silicic flows. On the other hand, flow banding is common in felsic flows. The morphology of lava describes its surface form or texture. More fluid basaltic lava flows tend to form flat sheet-like bodies, whereas viscous rhyolite lava flows form knobbly, blocky masses of rock. Lava erupted underwater has its own distinctive characteristics. ʻAʻā (also spelled aa , aʻa , ʻaʻa , and a-aa , and pronounced [ʔəˈʔaː] or / ˈ ɑː ( ʔ ) ɑː / )

3456-517: The flow of water and mud down the flanks of the volcano (a lahar ) after heavy rain . Solidified lava on the Earth's crust is predominantly silicate minerals : mostly feldspars , feldspathoids , olivine , pyroxenes , amphiboles , micas and quartz . Rare nonsilicate lavas can be formed by local melting of nonsilicate mineral deposits or by separation of a magma into immiscible silicate and nonsilicate liquid phases . Silicate lavas are molten mixtures dominated by oxygen and silicon ,

3528-585: The help of their teachers, a professor of linguistics, and a man who had been conducting a years-long project to collect Native American placenames in the area, in changing the names of several places that they had spotted in class one day and challenged for being racist, including renaming "Negrohead Creek" to an Athabascan name Lochenyatth Creek and "Negrohead Mountain" to Tl'oo Khanishyah Mountain, both of which translate to "grassy tussocks" in Lower Tanana and Gwichʼin respectively. Likewise, in researching

3600-497: The icy satellites of the Solar System 's giant planets . The lava's viscosity mostly determines the behavior of lava flows. While the temperature of common silicate lava ranges from about 800 °C (1,470 °F) for felsic lavas to 1,200 °C (2,190 °F) for mafic lavas, its viscosity ranges over seven orders of magnitude, from 10 cP (10 Pa⋅s) for felsic lavas to 10 cP (10 Pa⋅s) for mafic lavas. Lava viscosity

3672-404: The lava's chemical composition. This temperature range is similar to the hottest temperatures achievable with a forced air charcoal forge. Lava is most fluid when first erupted, becoming much more viscous as its temperature drops. Lava flows quickly develop an insulating crust of solid rock as a result of radiative loss of heat. Thereafter, the lava cools by a very slow conduction of heat through

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3744-610: The lava. Other cations , such as ferrous iron, calcium, and magnesium, bond much more weakly to oxygen and reduce the tendency to polymerize. Partial polymerization makes the lava viscous, so lava high in silica is much more viscous than lava low in silica. Because of the role of silica in determining viscosity and because many other properties of a lava (such as its temperature) are observed to correlate with silica content, silicate lavas are divided into four chemical types based on silica content: felsic , intermediate , mafic , and ultramafic . Felsic or silicic lavas have

3816-425: The location of the feature's mouth, or of the approximate center of the area of the feature. Such approximate centers were "eye-balled" estimates by the people performing the digitization, subject to the constraint that centers of areal features were not placed within other features that are inside them. alluvial fans and river deltas counted as mouths for this purpose. For cities and other large populated places,

3888-464: The lower and upper boundaries. These are described as pipe-stem vesicles or pipe-stem amygdales . Liquids expelled from the cooling crystal mush rise upwards into the still-fluid center of the cooling flow and produce vertical vesicle cylinders . Where these merge towards the top of the flow, they form sheets of vesicular basalt and are sometimes capped with gas cavities that sometimes fill with secondary minerals. The beautiful amethyst geodes found in

3960-467: The lower part that shows columnar jointing is called the colonnade . (The terms are borrowed from Greek temple architecture.) Likewise, regular vertical patterns on the sides of columns, produced by cooling with periodic fracturing, are described as chisel marks . Despite their names, these are natural features produced by cooling, thermal contraction, and fracturing. As lava cools, crystallizing inwards from its edges, it expels gases to form vesicles at

4032-422: The mantle than subalkaline magmas. Olivine nephelinite lavas are both ultramafic and highly alkaline, and are thought to have come from much deeper in the mantle of the Earth than other lavas. Tholeiitic basalt lava Rhyolite lava Some lavas of unusual composition have erupted onto the surface of the Earth. These include: The term "lava" can also be used to refer to molten "ice mixtures" in eruptions on

4104-521: The minimal heat loss maintains a low viscosity. The surface texture of pāhoehoe flows varies widely, displaying all kinds of bizarre shapes often referred to as lava sculpture. With increasing distance from the source, pāhoehoe flows may change into ʻaʻā flows in response to heat loss and consequent increase in viscosity. Experiments suggest that the transition takes place at a temperature between 1,200 and 1,170 °C (2,190 and 2,140 °F), with some dependence on shear rate. Pahoehoe lavas typically have

4176-717: The most such names being Arizona. One of the two standard reference works for placenames in Arizona is Byrd Howell Granger's 1983 book Arizona's Names: X Marks the Place , which contains many additional names with racial slurs not in the GNIS database. Despite "Nigger" having been removed from federal government use by Stewart Udall , its replacement "Negro" still remained in GNIS names in 2015, as did " Pickaninny ", " Uncle Tom ", and " Jim Crow " and 33 places named "Niggerhead". There were 828 names containing "squaw", including 11 variations on "Squaw Tit" and "Squaw Teat", contrasting with

4248-446: The physical behavior of silicate magmas. Silicon ions in lava strongly bind to four oxygen ions in a tetrahedral arrangement. If an oxygen ion is bound to two silicon ions in the melt, it is described as a bridging oxygen, and lava with many clumps or chains of silicon ions connected by bridging oxygen ions is described as partially polymerized. Aluminium in combination with alkali metal oxides (sodium and potassium) also tends to polymerize

4320-604: The point where a dam is thought to be". The National Geographic Names database (NGNDB hereafter) was originally 57 computer files, one for each state and territory of the United States (except Alaska which got two) plus one for the District of Columbia. The second Alaska file was an earlier database, the Dictionary of Alaska Place Names that had been compiled by the USGS in 1967. A further two files were later added, covering

4392-440: The range of 850 to 1,100 °C (1,560 to 2,010 °F). Because of their lower silica content and higher eruptive temperatures, they tend to be much less viscous, with a typical viscosity of 3.5 × 10 cP (3,500 Pa⋅s) at 1,200 °C (2,190 °F). This is slightly greater than the viscosity of smooth peanut butter . Intermediate lavas show a greater tendency to form phenocrysts . Higher iron and magnesium tends to manifest as

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4464-409: The rate of flow is proportional to the shear stress . Instead, a typical lava is a Bingham fluid , which shows considerable resistance to flow until a stress threshold, called the yield stress, is crossed. This results in plug flow of partially crystalline lava. A familiar example of plug flow is toothpaste squeezed out of a toothpaste tube. The toothpaste comes out as a semisolid plug, because shear

4536-539: The rocky crust. For instance, geologists of the United States Geological Survey regularly drilled into the Kilauea Iki lava lake, formed in an eruption in 1959. After three years, the solid surface crust, whose base was at a temperature of 1,065 °C (1,949 °F), was still only 14 m (46 ft) thick, even though the lake was about 100 m (330 ft) deep. Residual liquid was still present at depths of around 80 m (260 ft) nineteen years after

4608-412: The same rules as for the NGNDB. So too did names with diacritic characters. Phase 2 was broader in scope than phase 1, extending the scope to a much larger set of data sources. It ran from the end of phase 1 and had managed to completely process data from 42 states by 2003, with 4 still underway and the remaining 4 (Alaska, Kentucky, Michigan, and New York) awaiting the initial systematic compilation of

4680-455: The sources to use. Many more feature classes were included, including abandoned Native American settlements, ghost towns , railway stations on railway lines that no longer existed, housing developments , shopping centers , and highway rest areas . The actual compilation was outsourced by the U.S. government, state by state, to private entities such as university researchers. The Antarctica Geographic Names database (AGNDB hereafter)

4752-510: The use of "Nipple" in names with non- Native American allusions such as "Susies Nipple". Lava flow Lava is molten or partially molten rock ( magma ) that has been expelled from the interior of a terrestrial planet (such as Earth ) or a moon onto its surface. Lava may be erupted at a volcano or through a fracture in the crust , on land or underwater, usually at temperatures from 800 to 1,200 °C (1,470 to 2,190 °F). The volcanic rock resulting from subsequent cooling

4824-757: Was added in the 1990s and comprised records for BGN-approved names in Antarctica and various off-lying islands such as the South Orkney Islands , the South Shetland Islands , the Balleny Islands , Heard Island , South Georgia , and the South Sandwich Islands . It only contained records for natural features, not for scientific outposts. The media on which one could obtain the databases were extended in

4896-449: Was an actual elevation recorded for the map feature. They were of either the lowest or highest point of the feature, as appropriate. Interpolated elevations, calculated by interpolation between contour lines , were added in phase 2. Names were the official name, except where the name contained diacritic characters that the computer file encodings of the time could not handle (which were in phase 1 marked with an asterisk for update in

4968-492: Was never begun. The database is part of a system that includes topographic map names and bibliographic references. The names of books and historic maps that confirm the feature or place name are cited. Variant names, alternatives to official federal names for a feature, are also recorded. Each feature receives a permanent, unique feature record identifier, sometimes called the GNIS identifier. The database never removes an entry, "except in cases of obvious duplication." The GNIS

5040-442: Was originally designed for four major purposes: to eliminate duplication of effort at various other levels of government that were already compiling geographic data, to provide standardized datasets of geographic data for the government and others, to index all of the names found on official U.S. government federal and state maps, and to ensure uniform geographic names for the federal government. Phase 1 lasted from 1978 to 1981, with

5112-480: Was recorded following the collapse of a lava lake at Mount Nyiragongo . The scaling relationship for lavas is that the average speed of a flow scales as the square of its thickness divided by its viscosity. This implies that a rhyolite flow would have to be about a thousand times thicker than a basalt flow to flow at a similar speed. The temperature of most types of molten lava ranges from about 800 °C (1,470 °F) to 1,200 °C (2,190 °F) depending on

5184-568: Was undocumented, and it was (in the words of a 1986 report from the Engineer Topographic Laboratories of the United States Army Corps of Engineers ) "an unreasonable determination", with the likes of Cayuga Lake being labelled a "tank". The USACE report assumed that "tank" meant "reservoir", and observed that often the coordinates of "tanks" were outside of their boundaries and were "possibly at

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