Phoenix is the capital and most populous city of Arizona, with 1,626,000 people. It is the fifth most populous city in the United States, the most populous American state capital, the only state capital with a population of more than one million residents. Phoenix is the anchor of the Phoenix metropolitan area known as the Valley of the Sun, which in turn is part of the Salt River Valley; the metropolitan area is the 11th largest by population in the United States, with 4.73 million people as of 2017. Phoenix is the seat of Maricopa County and the largest city in the state at 517.9 square miles, more than twice the size of Tucson and one of the largest cities in the United States. Phoenix was settled in 1867 as an agricultural community near the confluence of the Salt and Gila Rivers and was incorporated as a city in 1881, it became the capital of Arizona Territory in 1889. It has a hot desert climate. Despite this, its canal system led to a thriving farming community with the original settler's crops remaining important parts of the Phoenix economy for decades, such as alfalfa, cotton and hay.
Cotton, citrus and copper were known locally as the "Five C's" anchoring Phoenix's economy. These remained the driving forces of the city until after World War II, when high-tech companies began to move into the valley and air conditioning made Phoenix's hot summers more bearable; the city averaged a four percent annual population growth rate over a 40-year period from the mid-1960s to the mid-2000s. This growth rate slowed during the Great Recession of 2007–09, has rebounded slowly. Phoenix is the cultural center of the state of Arizona; the Hohokam people occupied the Phoenix area for 2,000 years. They created 135 miles of irrigation canals, making the desert land arable, paths of these canals were used for the Arizona Canal, Central Arizona Project Canal, the Hayden-Rhodes Aqueduct, they carried out extensive trade with the nearby Ancient Puebloans and Sinagua, as well as with the more distant Mesoamerican civilizations. It is believed that periods of drought and severe floods between 1300 and 1450 led to the Hohokam civilization's abandonment of the area.
After the departure of the Hohokam, groups of Akimel O'odham, Tohono O'odham, Maricopa tribes began to use the area, as well as segments of the Yavapai and Apache. The O'odham were offshoots of the Sobaipuri tribe, who in turn were thought to be the descendants of the Hohokam; the Akimel O'odham were the major group in the area and lived in small villages, with well-defined irrigation systems that spread over the entire Gila River Valley, from Florence in the east to the Estrellas in the west. Their crops included corn and squash for food, while cotton and tobacco were cultivated, they banded together with the Maricopa for protection against incursions by the Yuma and Apache tribes. The Maricopa are part of the larger Yuma people; the Tohono O'odham lived in the region, as well, but their main concentration was to the south and stretched all the way to the Mexican border. The O'odham lived in small settlements as seasonal farmers who took advantage of the rains, rather than the large-scale irrigation of the Akimel.
They grew crops such as sweet corn, tapery beans, lentils, sugar cane, melons, as well as taking advantage of native plants such as saguaro fruits, cholla buds, mesquite tree beans, mesquite candy. They hunted local game such as deer and javelina for meat; the Mexican–American War ended in 1848, Mexico ceded its northern zone to the United States, residents of that region became U. S. citizens. The Phoenix area became part of the New Mexico Territory. In 1863, the mining town of Wickenburg was the first to be established in Maricopa County, to the northwest of Phoenix. Maricopa County had not yet been incorporated; the Army created Fort McDowell on the Verde River in 1865 to forestall Indian uprisings. The fort established a camp on the south side of the Salt River by 1866, the first settlement in the valley after the decline of the Hohokam. Other nearby settlements merged to become the city of Tempe; the history of the city of Phoenix begins with Jack Swilling, a Confederate veteran of the Civil War.
He saw a potential for farming. He formed a small community that same year about four miles east of the city. Lord Darrell Duppa was one of the original settlers in Swilling's party, he suggested the name "Phoenix", as it described a city born from the ruins of a former civilization; the Board of Supervisors in Yavapai County recognized the new town on May 4, 1868, the first post office was established the following month with Swilling as the postmaster. On February 12, 1871, the territorial legislature created Maricopa County by dividing Yavapai County; the first election for county office was held in 1871. He ran unopposed; the town grew during the 1870s, President Ulysses S. Grant issued a land patent for the site of Phoenix on April 10, 1874. By 1875, the town had a telegraph office
Little Colorado River
The Little Colorado River is a tributary of the Colorado River in the U. S. state of Arizona, providing the principal drainage from the Painted Desert region. Together with its major tributary, the Puerco River, it drains an area of about 26,500 square miles in eastern Arizona and western New Mexico. Although it stretches 340 miles, only the headwaters and the lowermost reaches flow year-round. Between St. Johns and Cameron, most of the river is a wide, braided wash, only containing water after heavy snowmelt or flash flooding; the lower 57.2 miles is known as the Little Colorado River Gorge and forms one of the largest arms of the Grand Canyon, at over 3,000 feet deep where it joins the Colorado near Desert View in Grand Canyon National Park. The river rises in Apache County; the West Fork starts in a valley on the north flank of Mount Baldy at an elevation of nearly 10,000 feet, while the East Fork starts nearby. The forks meet in a canyon near the town of Greer, it flows into River Reservoir leaves the canyon near Eagar.
The river turns north, meandering through Richville Valley, before emptying into Lyman Lake, impounded by an irrigation dam built in 1912. From there the river continues north, past the town of St. Johns. Shortly afterwards, the river transforms from a perennial stream to an ephemeral wash as it travels northwestwards through Hunt Valley, where it receives the Zuni River receiving Silver Creek and the Puerco River—its main tributaries—near the town of Holbrook as it flows into the Painted Desert; the Little Colorado passes Joseph City and crosses the Southern Transcon route of the BNSF Railway, now winding north into Coconino County. The river enters the Navajo Nation, drops over the 185-foot Grand Falls of the Little Colorado shortly after. Below Grand Falls, the river flows through a rugged canyon for about 15 miles. Emerging into the desert again, the Little Colorado skirts the eastern edge of Wupatki National Monument and passes the town of Cameron, where it is bridged by U. S. Highway 89.
From Cameron, the Little Colorado River carves an steep and narrow gorge into the Colorado Plateau achieving a maximum depth of about 3,200 feet. The depth of the canyon is such that groundwater is forced to the surface, forming numerous springs that restore a perennial river flow, it joins the Colorado deep inside miles from any major settlement. The confluence marks the end of the Marble Canyon segment of the Grand Canyon and the beginning of Upper Granite Gorge; the Little Colorado River is one of the two major tributaries of the Colorado River in Arizona, the other being the Gila River. Runoff peaks twice a year, first in the early spring from snow melt and highland rain; the annual runoff is variable with the possibility of no flow occurring due to a weak snow pack or lack of summer rain. Conversely, years such as 1949, 1973, 1979, 1983 and 1993 have seen massive volumes of spring snowmelt while large monsoon runoff has occurred in 1955, 1964, 1984 and 2006. Monthly average flows in the springtime average several hundred cfs and can reach 2,000 to 3,000 cubic feet per second.
Only the upper reaches of the river above St. Johns, the lowermost stretch below Cameron, flow year round. According to a streamflow gauge near Cameron, before the river enters the Grand Canyon, the river's average annual flow was 367.2 cubic feet per second from 1948 to present. The highest annual average was 1,127 cubic feet per second in 1973, the lowest was 14.1 cubic feet per second in 2000. The river's peak flows can be far higher than its average flow, because of quick desert runoff from cloudbursts. At the same gauge, peak flows were recorded from 1923 to 2008, with spotty data from 1924 to 1947; the highest recorded peak was 120,000 cubic feet per second on September 20, 1923, while the lowest was 1,590 cubic feet per second in 1974. Human activity in the Little Colorado River watershed dates back to the early Holocene epoch, in the last glacial period. Nomadic hunter-gatherers inhabited the water-rich and diverse upper basin of the Little Colorado for 8,000 years before the Navajo and Hopi tribes populated the area.
Many of these people practiced small-scale irrigation in riverside villages, located in sheltered canyons and cliffs that provided defense. Early Spanish explorers exploring the Grand Canyon area were most the first Europeans to see the Little Colorado River, they called it the Little Colorado. Other than fur trappers and mountain men, one of the first organized expeditions into the area of the Little Colorado River was led by Amiel Weeks Whipple in 1853–54 during one of the expeditions to map out a route for a transcontinental railroad. Called The Great Railroad Expeditions, or Pacific Railroad Surveys, Whipple's expedition consisted of several teams going along the 35th parallel from Albuquerque to the Pacific, following the Santa Fe Trail route; the Little Colorado River known as the Flax River, the first Rio Chiquito, is depicted and labelled as such on a map compiled by Lt. Joseph C. Ives and published in the official volumes of those expeditions. Ives would again return to the area in 1858 after navigating a steamboat named the Explorer up the Colorado from south of Yuma northwards to Black Canyon, at which point his party went
Petrified wood is the name given to a special type of fossilized remains of terrestrial vegetation. It is the result of a tree or tree-like plants having transitioned to stone by the process of permineralization. All the organic materials have been replaced with minerals, while retaining the original structure of the stem tissue. Unlike other types of fossils which are impressions or compressions, petrified wood is a three-dimensional representation of the original organic material; the petrifaction process occurs underground, when wood becomes buried under sediment or volcanic ash and is preserved due to a lack of oxygen which inhibits aerobic decomposition. Mineral-laden water flowing through the covering material deposits minerals in the plant's cells; the organic matter needs to become petrified. The process lasts millions of years. A forest where such material has petrified becomes known as a petrified forest. Elements such as manganese and copper in the water/mud during the petrification process give petrified wood a variety of color ranges.
Pure quartz crystals are colorless, but when contaminants are added to the process the crystals take on a yellow, red, or another tint. Following is a list of contaminating elements and related color hues: carbon – black chromium – green/blue cobalt – green/blue copper – green/blue iron oxides – red and yellow manganese – pink/orange manganese oxides – blackish/yellow silicon dioxide – clear/white/greyPetrified wood can preserve the original structure of the stem in all its detail, down to the microscopic level. Structures such as tree rings and the various tissues are observed features. Petrified wood is a fossil in which the organic remains have been replaced by minerals in the slow process of being replaced with stone; this petrification process results in a quartz chalcedony mineralization. Special rare conditions must be met in order for the fallen stem to be transformed into fossil wood or petrified wood. In general, the fallen plants get buried in an environment free of oxygen, which preserves the original plant structure and general appearance.
The other conditions include a regular access to mineral rich water in contact with the tissues, replacing the organic plant structure with inorganic minerals. The end result is petrified wood, a plant, with its original basic structure in place, replaced by stone. Exotic minerals allow the green hues that can be seen in rarer specimens. Areas with a large number of petrified trees include: Argentina – the Sarmiento Petrified Forest and Jaramillo Petrified Forest in Santa Cruz Province in the Argentine Patagonia have many trees that measure more than 3 m in diameter and 30 m long. Australia -- has deposits of opalised wood. Chinchilla, Queensland is famous for its'Chinchilla Red'. Belgium – Geosite Goudberg near Hoegaarden. Brazil: in the geopark of Paleorrota, there is a vast area with petrified trees. Monumento Natural das Árvores Fossilizadas in Tocantins: petrified forests of dicksoniaceae and arthropitys Petrified forests of dicksoniaceae and arthropitys can be found in the state of São Paulo Floresta Fóssil de Teresina near Rio Poti, Piauí, Permian.
Canada – in the badlands of southern Alberta. Axel Heiberg Island in Nunavut has a large petrified forest. In and around the North Saskatchewan river, around the Edmonton area. Blanche Brook, in Stephenville, has 305-million-year-old examples. China – in the Junggar Basin of Xinjiang, northwest China government has issued a crackdown on collecting of this material. Czech Republic, Nová Paka – The most famous locality on Permian–Carboniferous rocks in the Czech Republic. Ecuador – Puyango Petrified Forest – One of the largest collections of petrified wood in the world. Egypt – petrified forest in Cairo-Suez road, declared a national protectorate by the ministry of environment in the area of New Cairo at the Extension of Nasr City, El Qattamiyya, near El Maadi district, Al Farafra oasis. France – petrified forest in the village of Champclauson Georgia – Goderdzi Petrified Forest Natural Monument. Germany – the museum of natural history in Chemnitz has a collection of petrified trees, from the in situ Chemnitz petrified forest, found in the town since 1737.
Greece – Petrified forest of Lesvos, at the western tip of the island of Lesbos, is the largest of the petrified forests, covering an area of over 150 km2 and declared a National Monument in 1985. Large, upright trunks complete with root systems can be found, as well as trunks up to 22 m in length. India – protected geological sites known for petrified wood are the National Fossil Wood Park and the Akal Wood Fossil Park. Petrified wood has been discovered in Dholavira in Kutch, dating back to 187–176 million years. Indonesia – petrified wood covers several area in Banten and in some part of Mount Halimun Salak National Park. Israel – several examples of petrified wood occur in the HaMakhtesh HaGadol in the Negev desert. Italy: Foresta fossile di Dunarobba, petrified forest near Avigliano Umbro, age Piacenzian. Foresta pietrificata di Zuri – Soddì, petrified forest near Soddì, age Chattian–Aquitanian. Libya – Great Sand Sea – Hundreds of s
The Pinophyta known as Coniferophyta or Coniferae, or as conifers, are a division of vascular land plants containing a single extant class, Pinopsida. They are gymnosperms, cone-bearing seed plants. All extant conifers are perennial woody plants with secondary growth; the great majority are trees. Examples include cedars, Douglas firs, firs, kauri, pines, redwoods and yews; as of 1998, the division Pinophyta was estimated to contain eight families, 68 genera, 629 living species. Although the total number of species is small, conifers are ecologically important, they are the dominant plants over large areas of land, most notably the taiga of the Northern Hemisphere, but in similar cool climates in mountains further south. Boreal conifers have many wintertime adaptations; the narrow conical shape of northern conifers, their downward-drooping limbs, help them shed snow. Many of them seasonally alter their biochemistry to make them more resistant to freezing. While tropical rainforests have more biodiversity and turnover, the immense conifer forests of the world represent the largest terrestrial carbon sink.
Conifers are of great economic value for softwood paper production. The earliest conifers in the fossil record date to the late Carboniferous period arising from Cordaites, a genus of seed-bearing Gondwanan plants with cone-like fertile structures. Pinophytes and Ginkgophytes all developed at this time. An important adaptation of these gymnosperms was allowing plants to live without being so dependent on water. Other adaptations are pollen and the seed, which allows the embryo to be transported and developed elsewhere. Conifers appear to be one of the taxa that benefited from the Permian–Triassic extinction event, were the dominant land plants of the Mesozoic, they were overtaken by the flowering plants, which first appeared in the Cretaceous, became dominant in the Cenozoic era. They were the main food of herbivorous dinosaurs, their resins and poisons would have given protection against herbivores. Reproductive features of modern conifers had evolved by the end of the Mesozoic era. Conifer is a Latin word, a compound of conus and ferre, meaning "the one that bears cone".
The division name Pinophyta conforms to the rules of the International Code of Nomenclature for algae and plants, which state that the names of higher taxa in plants are either formed from the name of an included family, in this case Pinaceae, or are descriptive. A descriptive name in widespread use for the conifers is Coniferae. According to the ICN, it is possible to use a name formed by replacing the termination -aceae in the name of an included family, in this case preferably Pinaceae, by the appropriate termination, in the case of this division ‑ophyta. Alternatively, "descriptive botanical names" may be used at any rank above family. Both are allowed; this means that if conifers are considered a division, they may be called Coniferae. As a class they may be called Coniferae; as an order they may be called Coniferae or Coniferales. Conifers are the largest and economically most important component group of the gymnosperms, but they comprise only one of the four groups; the division Pinophyta consists of just one class, which includes both living and fossil taxa.
Subdivision of the living conifers into two or more orders has been proposed from time to time. The most seen in the past was a split into two orders and Pinales, but recent research into DNA sequences suggests that this interpretation leaves the Pinales without Taxales as paraphyletic, the latter order is no longer considered distinct. A more accurate subdivision would be to split the class into three orders, Pinales containing only Pinaceae, Araucariales containing Araucariaceae and Podocarpaceae, Cupressales containing the remaining families, but there has not been any significant support for such a split, with the majority of opinion preferring retention of all the families within a single order Pinales, despite their antiquity and diverse morphology; the conifers are now accepted as comprising seven families, with a total of 65–70 genera and 600–630 species. The seven most distinct families are linked in the box above right and phylogenetic diagram left. In other interpretations, the Cephalotaxaceae may be better included within the Taxaceae, some authors additionally recognize Phyllocladaceae as distinct from Podocarpaceae.
The family Taxodiaceae is here included in family Cupressaceae, but was recognized in the past and can still be found in many field guides. A new classification and linear sequence based on molecular data can be found in an article by Christenhusz et al; the conifers are an ancient group, with a fossil record extending back about 300 million years to the Paleozoic in the late Carboniferous period. Other classes and orders, now long extinct occur as fossils from the late Paleozoic and Mesozoic eras. Fossil conifers included many diverse forms, the most distinct from modern conifers being some herbaceous conifers with no woody stems. Major fossil orders of conifers or conifer-like plants include the Cordaitales, Vojnovskyales and also the Czekanowskiales (possibly
Petrified Forest National Park
Petrified Forest National Park is an American national park in Navajo and Apache counties in northeastern Arizona. Named for its large deposits of petrified wood, the fee area of the park covers about 230 square miles, encompassing semi-desert shrub steppe as well as eroded and colorful badlands; the park's headquarters is about 26 miles east of Holbrook along Interstate 40, which parallels the BNSF Railway's Southern Transcon, the Puerco River, historic U. S. Route 66, all crossing the park east–west; the site, the northern part of which extends into the Painted Desert, was declared a national monument in 1906 and a national park in 1962. The park received 644,922 recreational visitors in 2018. Typical visitor activities include sightseeing, photography and backpacking. Averaging about 5,400 feet in elevation, the park has a dry windy climate with temperatures that vary from summer highs of about 100 °F to winter lows well below freezing. More than 400 species of plants, dominated by grasses such as bunchgrass, blue grama, sacaton, are found in the park.
Fauna include larger animals such as pronghorns and bobcats, many smaller animals, such as deer mice, lizards, seven kinds of amphibians, more than 200 species of birds, some of which are permanent residents and many of which are migratory. About one third of the park is designated wilderness—50,260 acres; the Petrified Forest is known for its fossils fallen trees that lived in the Late Triassic Epoch, about 225 million years ago. The sediments containing the fossil logs are part of the widespread and colorful Chinle Formation, from which the Painted Desert gets its name. Beginning about 60 million years ago, the Colorado Plateau, of which the park is part, was pushed upward by tectonic forces and exposed to increased erosion. All of the park's rock layers above the Chinle, except geologically recent ones found in parts of the park, have been removed by wind and water. In addition to petrified logs, fossils found in the park have included Late Triassic ferns, cycads and many other plants as well as fauna including giant reptiles called phytosaurs, large amphibians, early dinosaurs.
Paleontologists have been studying the park's fossils since the early 20th century. The park's earliest human inhabitants arrived at least 8,000 years ago. By about 2,000 years ago, they were growing corn in the area and shortly thereafter building pit houses in what would become the park. Inhabitants built above-ground dwellings called pueblos. Although a changing climate caused the last of the park's pueblos to be abandoned by about 1400 CE, more than 600 archeological sites, including petroglyphs, have been discovered in the park. In the 16th century, Spanish explorers visited the area, by the mid-19th century a U. S. team had surveyed an east–west route through the area where the park is now located and noted the petrified wood. Roads and a railway followed similar routes and gave rise to tourism and, before the park was protected, to large-scale removal of fossils. Theft of petrified wood remains a problem in the 21st century. Petrified Forest National Park straddles the border between Apache County and Navajo County in northeastern Arizona.
The park is about 30 miles long from north to south, its width varies from a maximum of about 12 miles in the north to a minimum of about 1 mile along a narrow corridor between the north and south, where the park widens again to about 4 to 5 miles. I-40, former U. S. Route 66, the BNSF Railway, the Puerco River bisect the park east–west along a similar route. Adamana, a ghost town, is about 1 mile west of the park along the BNSF tracks. Holbrook, about 26 miles west of park headquarters along I-40, is the nearest city. Bisecting the park north–south is Park Road, which runs between I-40 near park headquarters on the north and U. S. Route 180 on the south. Historic Highway 180, an earlier alignment of the modern route, crosses the southern edge of the park. Like Route 66, it is closed. Many unpaved maintenance roads, closed to the public, intersect Park Road at various points; the fee area of the park covers about 230 square miles. The Navajo Nation borders the park on the northeast. State-owned land, federal land controlled by the Bureau of Land Management, private land, much of it used for cattle ranching, adjoin the other borders.
The park’s elevation above sea level varies from a low of 5,340 feet along the Puerco River to a high of 6,230 feet at Pilot Rock. The terrain varies from gentle hills and major petrified wood deposits in the south to eroded badlands in the north. Most of the park's intermittent streams—including Lithodendron Wash, Dead Wash, Ninemile Wash, Dry Wash—empty into the Puerco River. In the southern part of the park, Cottonwood Wash and Jim Camp Wash flow into the Little Colorado River. Petrified Forest National Park is known for its fossils of fallen trees that lived in the Late Triassic Epoch of the Mesozoic era, about 225 million years ago. During this period, the region, now the park was near the equator on the southwestern edge of the supercontinent Pangaea, its climate was humid and sub-tropical. What became northeastern Arizona was a low plain flanked by mountains to the south and southeast and a sea to the west. Streams flowing across the plain from the highlands deposited inorganic sediment and organic matter, including trees as well as other plants and animals that had entered or fallen into the water.
Although most organic matter decays or is eaten by other organisms, some is
Siltstone is a sedimentary rock which has a grain size in the silt range, finer than sandstone and coarser than claystones. Siltstone is a clastic sedimentary rock; as its name implies, it is composed of silt sized particles, defined as grains 2–62 µm or 4 to 8 on the Krumbein phi scale. Siltstones differ from sandstones due to their smaller pores and higher propensity for containing a significant clay fraction. Although mistaken as a shale, siltstone lacks the fissility and laminations which are typical of shale. Siltstones may contain concretions. Unless the siltstone is shaly, stratification is to be obscure and it tends to weather at oblique angles unrelated to bedding. Mudstone or shale are rocks that contain mud, material that has a range of silt and clay. Siltstone is differentiated by having a majority silt, not clay. Cosmetic palette—made exclusively out of siltstone with a few exceptions Folk, R. L. 1965, Petrology of sedimentary rocks PDF version. Austin: Hemphill’s Bookstore. 2nd ed. 1981, ISBN 0-914696-14-9 Williams, Francis J. Turner and Charles M. Gilbert, 1954, Petrography, W. H. Freeman
United States Geological Survey
The United States Geological Survey is a scientific agency of the United States government. The scientists of the USGS study the landscape of the United States, its natural resources, the natural hazards that threaten it; the organization has four major science disciplines, concerning biology, geography and hydrology. The USGS is a fact-finding research organization with no regulatory responsibility; the USGS is a bureau of the United States Department of the Interior. The USGS employs 8,670 people and is headquartered in Reston, Virginia; the USGS has major offices near Lakewood, Colorado, at the Denver Federal Center, Menlo Park, California. The current motto of the USGS, in use since August 1997, is "science for a changing world." The agency's previous slogan, adopted on the occasion of its hundredth anniversary, was "Earth Science in the Public Service." Since 2012, the USGS science focus is directed at six topical "Mission Areas", namely Climate and Land Use Change, Core Science Systems, Ecosystems and Minerals and Environmental Health, Natural Hazards, Water.
In December 2012, the USGS split the Energy and Minerals and Environmental Health Mission Area resulting in seven topical Mission Areas, with the two new areas being: Energy and Minerals and Environmental Health. Administratively, it is divided into six Regional Units. Other specific programs include: Earthquake Hazards Program monitors earthquake activity worldwide; the National Earthquake Information Center in Golden, Colorado on the campus of the Colorado School of Mines detects the location and magnitude of global earthquakes. The USGS runs or supports several regional monitoring networks in the United States under the umbrella of the Advanced National Seismic System; the USGS informs authorities, emergency responders, the media, the public, both domestic and worldwide, about significant earthquakes. It maintains long-term archives of earthquake data for scientific and engineering research, it conducts and supports research on long-term seismic hazards. USGS has released the UCERF California earthquake forecast.
As of 2005, the agency is working to create a National Volcano Early Warning System by improving the instrumentation monitoring the 169 volcanoes in U. S. territory and by establishing methods for measuring the relative threats posed at each site. The USGS National Geomagnetism Program monitors the magnetic field at magnetic observatories and distributes magnetometer data in real time; the USGS collaborates with Canadian and Mexican government scientists, along with the Commission for Environmental Cooperation, to produce the North American Environmental Atlas, used to depict and track environmental issues for a continental perspective. The USGS operates the streamgaging network for the United States, with over 7400 streamgages. Real-time streamflow data are available online. National Climate Change and Wildlife Science Center implements partner-driven science to improve understanding of past and present land use change, develops relevant climate and land use forecasts, identifies lands and communities that are most vulnerable to adverse impacts of change from the local to global scale.
Since 1962, the Astrogeology Research Program has been involved in global and planetary exploration and mapping. In collaboration with Stanford University, the USGS operates the USGS-Stanford Ion Microprobe Laboratory, a world-class analytical facility for U--Pb geochronology and trace element analyses of minerals and other earth materials. USGS operates a number of water related programs, notably the National Streamflow Information Program and National Water-Quality Assessment Program. USGS Water data is publicly available from their National Water Information System database; the USGS operates the National Wildlife Health Center, whose mission is "to serve the nation and its natural resources by providing sound science and technical support, to disseminate information to promote science-based decisions affecting wildlife and ecosystem health. The NWHC provides information, technical assistance, research and leadership on national and international wildlife health issues." It is the agency responsible for surveillance of H5N1 avian influenza outbreaks in the United States.
The USGS runs 17 biological research centers in the United States, including the Patuxent Wildlife Research Center. The USGS is investigating collaboration with the social networking site Twitter to allow for more rapid construction of ShakeMaps; the USGS produces several national series of topographic maps which vary in scale and extent, with some wide gaps in coverage, notably the complete absence of 1:50,000 scale topographic maps or their equivalent. The largest and best-known topographic series is the 7.5-minute, 1:24,000 scale, quadrangle, a non-metric scale unique to the United States. Each of these maps covers an area bounded by two lines of latitude and two lines of longitude spaced 7.5 minutes apart. Nearly 57,000 individual maps in this series cover the 48 contiguous states, Hawaii, U. S. territories, areas of Alaska near Anchorage and Prudhoe Bay. The area covered by each map varies with the latitude of its represented location due to convergence of the meridians. At lower latitudes, near 30° north, a 7.5-minute quadrangle contains an area of about 64 square miles.
At 49° north latitude, 49 square miles are contained within a quadrangle of that size. As a unique non-metric map scale, the 1:24,000 scale requires a separate and specialized romer scale for pl