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
Channel 4 is a British public-service free-to-air television network that began transmission on 2 November 1982. Although commercially-self-funded, it is publicly-owned. With the conversion of the Wenvoe transmitter group in Wales to digital terrestrial broadcasting on 31 March 2010, Channel 4 became a UK-wide TV channel for the first time; the channel was established to provide a fourth television service to the United Kingdom in addition to the licence-funded BBC One and BBC Two, the single commercial broadcasting network ITV. Before Channel 4 and S4C, Britain had three terrestrial television services: BBC1, BBC2, ITV; the Broadcasting Act 1980 began the process of adding a fourth, Channel 4, along with its Welsh counterpart, was formally created by an Act of Parliament in 1982. After some months of test broadcasts, it began scheduled transmissions on 2 November 1982; the notion of a second commercial broadcaster in the United Kingdom had been around since the inception of ITV in 1954 and its subsequent launch in 1955.
Indeed, television sets sold throughout the 1970s and early 1980s had a spare tuning button labelled "ITV/IBA 2". Throughout ITV's history and until Channel 4 became a reality, a perennial dialogue existed between the GPO, the government, the ITV companies and other interested parties, concerning the form such an expansion of commercial broadcasting would take, it was most politics which had the biggest impact in leading to a delay of three decades before the second commercial channel became a reality. One clear benefit of the "late arrival" of the channel was that its frequency allocations at each transmitter had been arranged in the early 1960s, when the launch of an ITV2 was anticipated; this led to good coverage across most of the country and few problems of interference with other UK-based transmissions. At the time the fourth service was being considered, a movement in Wales lobbied for the creation of dedicated service that would air Welsh-language programmes only catered for at "off peak" times on BBC Wales and HTV.
The campaign was taken so by Gwynfor Evans, former president of Plaid Cymru, that he threatened the government with a hunger strike were it not to honour the plans. The result was that Channel 4 as seen by the rest of the United Kingdom would be replaced in Wales by Sianel Pedwar Cymru. Operated by a specially created authority, S4C would air programmes in Welsh made by HTV, the BBC and independent companies. Limited frequency space meant that Channel 4 could not be broadcast alongside S4C, though some Channel 4 programmes would be aired at less popular times on the Welsh variant, a practice that carried on up until the closure of S4C's analogue transmissions in 2010 when S4C became a Welsh channel. Since carriage on digital cable and digital terrestrial has introduced Channel 4 to Welsh homes where it is now universally available; the first voice heard on Channel 4's opening day of Tuesday 2 November 1982 was that of continuity announcer Paul Coia who said: Good afternoon. It's a pleasure to be able to say to you, welcome to Channel Four.
Following the announcement, the channel headed into a montage of clips from its programmes set to the station's signature tune, "Fourscore", written by David Dundas, which would form the basis of the station's jingles for its first decade. The first programme to air on the channel was the teatime game show Countdown, at 16:45 produced by Yorkshire Television; the first person to be seen on Channel 4 was Richard Whiteley with Ted Moult being the second. The first woman on the channel, contrary to popular belief, was not Whiteley's Countdown co-host Carol Vorderman but a lexicographer only identified as Mary. Whiteley opened the show with the words: As the countdown to a brand new channel ends, a brand new countdown begins. On its first day, Channel 4 broadcast controversial soap opera Brookside, which ran until 2003. On its launch, Channel 4 committed itself to providing an alternative to the existing channels, an agenda in part set out by its remit which required the provision of programming to minority groups.
In step with its remit, the channel became well received both by minority groups and the arts and cultural worlds during this period under founding chief executive Jeremy Isaacs, where the channel gained a reputation for programmes on the contemporary arts. Channel 4 co-commissioned Robert Ashley's ground-breaking television opera Perfect Lives, which it premiered over several episodes in 1984; the channel did not receive mass audiences for much of this period, however, as might be expected for a station focusing on minority interest. Channel 4 began the funding of independent films, such as the Merchant-Ivory docudrama The Courtesans of Bombay, during this time. In 1992, Channel 4 faced its first libel case by Jani Allan, a South African journalist, who objected to her representation in Nick Broomfield's documentary The Leader, His Driver and the Driver's Wife. In September 1993, the channel broadcast the direct-to-TV documentary film Beyond Citizen Kane, in which it displayed the dominant position of the Rede Globo television network, discussed its influence and political connections in Brazil.
After control of the station passed from the Channel Four Television Co
East Antarctica called Greater Antarctica, constitutes the majority of the Antarctic continent, lying on the Indian Ocean side of the continent, separated from West Antarctica by the Transantarctic Mountains. It lies entirely within the Eastern Hemisphere and its name has been accepted for more than a century, it is higher than West Antarctica and includes the Gamburtsev Mountain Range in the centre. Apart from small areas of the coast, East Antarctica is permanently covered by ice; the only terrestrial plant life is lichens and algae clinging to rocks, there are a limited range of invertebrates including nematodes, springtails and midges. The coasts are the breeding ground for various seabirds and penguins, the leopard seal, Weddell seal, elephant seal, crabeater seal and Ross seal breed on the surrounding pack ice in summer. Covered in thick, permanent ice, East Antarctica comprises Coats Land, Queen Maud Land, Enderby Land, Kemp Land, Mac. Robertson Land, Princess Elizabeth Land, Wilhelm II Land, Queen Mary Land, Wilkes Land, Adélie Land, George V Land, Oates Land and Victoria Land.
All but a small portion of this region lies within the Eastern Hemisphere, a fact that has suggested the name. The name has been in existence for more than 90 years, but its greatest use followed the International Geophysical Year and explorations disclosing that the Transantarctic Mountains, provide a useful regional separation of East Antarctica and West Antarctica; the name was approved in the United States by the Advisory Committee on Antarctic Names in 1962. East Antarctica is higher than West Antarctica, is considered the coldest place on Earth; the subglacial Gamburtsev Mountain Range, about the size of the European Alps, in the center of East Antarctica, are believed to have been the nucleation site for the East Antarctic Ice Sheet, just underneath Dome A. Little of East Antarctica is not covered with ice; the small areas that remain free of ice, including the McMurdo Dry Valleys inland, constitute a tundra-type biodiversity region known as Maudlandia Antarctic desert, after Queen Maud Land.
There are no trees or shrubs, as only limited plant life can survive here. The coasts are home to seabirds and seals, which feed in the surrounding ocean, including the emperor penguin, which famously breeds in the cold, dark Antarctic winter. Seabirds of the coast include southern fulmar, the scavenging southern giant petrel, Cape petrel, snow petrel, the small Wilson's storm-petrel, the large south polar skua, Antarctic petrel; the seals of the Antarctic Ocean include leopard seal, Weddell seal, the huge southern elephant seal, crabeater seal and Ross seal. There are no large land animals but bacteria, springtails and midges live on the mosses and lichens; the remote and cold bulk of Antarctica remains entirely untouched by human intervention. The area is protected by the Antarctic Treaty System which bans industrial development, waste disposal and nuclear testing, while the Barwick Valley, one of the Dry Valleys, Cryptogam Ridge on Mount Melbourne are specially protected areas for their undisturbed plant life.
East Antarctic craton Polar plateau This article incorporates public domain material from the United States Geological Survey document "East Antarctica". World Wildlife Fund, C. M. Hogan, S. Draggan. Marielandia Antarctic tundra. in C. J. Cleveland, ed. Encyclopedia of Earth. National Council for Science and the Environment, Washington, DC
Thermohaline circulation is a part of the large-scale ocean circulation, driven by global density gradients created by surface heat and freshwater fluxes. The adjective thermohaline derives from thermo- referring to temperature and -haline referring to salt content, factors which together determine the density of sea water. Wind-driven surface currents travel polewards from the equatorial Atlantic Ocean, cooling en route, sinking at high latitudes; this dense water flows into the ocean basins. While the bulk of it upwells in the Southern Ocean, the oldest waters upwell in the North Pacific. Extensive mixing therefore takes place between the ocean basins, reducing differences between them and making the Earth's oceans a global system. On their journey, the water masses transport both mass of substances around the globe; as such, the state of the circulation has a large impact on the climate of the Earth. The thermohaline circulation is sometimes called the ocean conveyor belt, the great ocean conveyor, or the global conveyor belt.
On occasion, it is used to refer to the meridional overturning circulation. The term MOC is more accurate and well defined, as it is difficult to separate the part of the circulation, driven by temperature and salinity alone as opposed to other factors such as the wind and tidal forces. Moreover and salinity gradients can lead to circulation effects that are not included in the MOC itself; the movement of surface currents pushed by the wind is intuitive. For example, the wind produces ripples on the surface of a pond, thus the deep ocean—devoid of wind—was assumed to be static by early oceanographers. However, modern instrumentation shows that current velocities in deep water masses can be significant. In general, ocean water velocities range from fractions of centimeters per second to sometimes more than 1 m/s in surface currents like the Gulf Stream and Kuroshio. In the deep ocean, the predominant driving force is differences in density, caused by salinity and temperature variations. There is confusion over the components of the circulation that are wind and density driven.
Note that ocean currents due to tides are significant in many places. There they are thought to facilitate mixing processes diapycnal mixing; the density of ocean water is not globally homogeneous, but varies and discretely. Defined boundaries exist between water masses which form at the surface, subsequently maintain their own identity within the ocean, but these sharp boundaries are not to be imagined spatially but rather in a T-S-diagram where water masses are distinguished. They position themselves above or below each other according to their density, which depends on both temperature and salinity. Warm seawater is thus less dense than cooler seawater. Saltier water is denser than fresher water because the dissolved salts fill interstices between water molecules, resulting in more mass per unit volume. Lighter water masses float over denser ones; this is known as "stable stratification" as opposed to unstable stratification where denser waters are located over less dense waters. When dense water masses are first formed, they are not stably stratified, so they seek to locate themselves in the correct vertical position according to their density.
This motion is called it orders the stratification by gravitation. Driven by the density gradients this sets up the main driving force behind deep ocean currents like the deep western boundary current; the thermohaline circulation is driven by the formation of deep water masses in the North Atlantic and the Southern Ocean caused by differences in temperature and salinity of the water. The great quantities of dense water sinking at high latitudes must be offset by equal quantities of water rising elsewhere. Note that cold water in polar zones sink rapidly over a small area, while warm water in temperate and tropical zones rise more across a much larger area, it slowly returns poleward near the surface to repeat the cycle. The continual diffuse upwelling of deep water maintains the existence of the permanent thermocline found everywhere at low and mid-latitudes; this model was described by Henry Stommel and Arnold B. Arons in 1960 and is known as the Stommel-Arons box model for the MOC; this slow upward movement is approximated to be about 1 centimeter per day over most of the ocean.
If this rise were to stop, downward movement of heat would cause the thermocline to descend and would reduce its steepness. The dense water masses that sink into the deep basins are formed in quite specific areas of the North Atlantic and the Southern Ocean. In the North Atlantic, seawater at the surface of the ocean is intensely cooled by the wind and low ambient air temperatures. Wind moving over the water produces a great deal of evaporation, leading to a decrease in temperature, called evaporative cooling related to latent heat. Evaporation removes only water molecules, resulting in an increase in the salinity of the seawater left behind, thus an increase in the density of the water mass along with the decrease in tem
Sir Douglas Mawson OBE FRS FAA was an Australian geologist, Antarctic explorer, academic. Along with Roald Amundsen, Robert Falcon Scott, Sir Ernest Shackleton, he was a key expedition leader during the Heroic Age of Antarctic Exploration; the Mawson Station in the Australian Antarctic Territory is named in his honour. Mawson was born on 5 May 1882 to Margaret Ann Moore, he was born in Shipley, West Yorkshire, but was less than two years old when his family immigrated to Australia and settled at Rooty Hill, now in the western suburbs of Sydney. He attended Fort Street Model School and the University of Sydney, where he graduated in 1902 with a Bachelor of Engineering degree, he was appointed geologist to an expedition to the New Hebrides in 1903. That year he published a geological paper on Mittagong, New South Wales, his major influences in his geological career were Professor Edgeworth David and Professor Archibald Liversidge. He became a lecturer in petrology and mineralogy at the University of Adelaide in 1905.
He first described the mineral davidite. Mawson joined Ernest Shackleton's Nimrod Expedition to the Antarctic intending to stay for the duration of the ship's presence in the first summer. Instead both he and his mentor, Edgeworth David, stayed an extra year. In doing so they became, in the company of Alistair Mackay, the first to climb the summit of Mount Erebus and to trek to the South Magnetic Pole, which at that time was over land. Mawson turned down an invitation to join Robert Falcon Scott's Terra Nova Expedition in 1910. Mawson chose to lead his own expedition, the Australasian Antarctic Expedition, to King George V Land and Adelie Land, the sector of the Antarctic continent south of Australia, which at the time was entirely unexplored; the objectives were to carry out geographical exploration and scientific studies, including a visit to the South Magnetic Pole. Mawson raised the necessary funds in a year, from British and Australian governments, from commercial backers interested in mining and whaling.
The expedition, using the ship SY Aurora commanded by Captain John King Davis, departed from Hobart on 2 December 1911, landed at Cape Denison on Commonwealth Bay on 8 January 1912, established the Main Base. A second camp was located to the west on the ice shelf in Queen Mary Land. Cape Denison proved to be unrelentingly windy, they wintered through nearly constant blizzards. Mawson brought the first aeroplane to Antarctica; the aircraft, a Vickers R. E. P. Type Monoplane, was to be flown by Francis Howard Bickerton; when it was damaged in Australia shortly before the expedition departed, plans were changed so it was to be used only as a tractor on skis. However, the engine did not operate well in the cold, it was removed and returned to Vickers in England; the aircraft fuselage. On 1 January 2009, fragments of it were rediscovered by the Mawson's Huts Foundation, restoring the original huts. Mawson's exploration program was carried out by five parties from the Main Base and two from the Western Base.
Mawson himself was part of a three-man sledging team, the Far Eastern Party, with Xavier Mertz and Lieutenant Belgrave Ninnis, who headed east on 10 November 1912, to survey King George V Land. After five weeks of excellent progress mapping the coastline and collecting geological samples, the party was crossing the Ninnis Glacier 480 km east of the main base. Mertz was skiing and Mawson was on his sled with his weight dispersed, but Ninnis was jogging beside the second sled. Ninnis fell through a crevasse, his body weight is to have breached the snow bridge covering it; the six best dogs, most of the party's rations, their tent, other essential supplies disappeared into the massive crevasse. Mertz and Mawson spotted one dead and one injured dog on a ledge 165 ft below them, but Ninnis was never seen again. After a brief service and Mertz turned back immediately, they had plenty of fuel and a primus. They sledged for 27 hours continuously to obtain a spare tent cover they had left behind, for which they improvised a frame from skis and a theodolite.
Their lack of provisions forced them to use their remaining sled dogs to feed the other dogs and themselves: Their meat was stringy and without a vestige of fat. For a change we sometimes chopped it up finely, mixed it with a little pemmican, brought all to the boil in a large pot of water. We were exceedingly hungry. Only a few ounces were used of the stock of ordinary food, to, added a portion of dog's meat, never large, for each animal yielded so little, the major part was fed to the surviving dogs, they ate the skin, until nothing remained. There was a quick deterioration in the men's physical condition during this journey. Both men suffered dizziness. Mawson noticed a dramatic change in his travelling companion. Mertz wished only to remain in his sleeping bag, he began to deteriorate with diarrhoea and madness. On one occasion Mertz refused to believe he was suffering from frostbite and bit off the
A fast-moving ice or ice stream is a region of an ice sheet that moves faster than the surrounding ice. Ice streams are a type of glacier, they are significant features of the Antarctic. They are up to 50 kilometres wide, 2 km thick, can stretch for hundreds of kilometres, account for most of the ice leaving the ice sheet; the speed of an ice stream can be over 1,000 metres per year, an order of magnitude faster than the surrounding ice. The shear forces at the edge of the ice stream cause deformation and recrystallization of the ice, making it softer, concentrating the deformation in narrow bands or shear margins. Crevasses form around the shear margins. Most ice streams have some water at their base; the type of bedrock is significant. Soft, deformable sediments result in faster flow than hard rock; the Antarctic Ice Sheet is drained to the sea by several ice streams. The largest in East Antarctica is Lambert Glacier. In West Antarctica the large Pine Island and Thwaites Glaciers are the most out of balance, with a total net mass loss between them of 85 gigatonnes per year measured in 2006.
It has been suggested. The past and ongoing acceleration of ice streams and outlet glaciers is considered to be a significant, if not the dominant cause of this recent imbalance. Ice streams that drain the Greenland ice sheet into the sea include Helheim Glacier, Jakobshavn Isbræ and Kangerdlugssuaq Glacier. Fits and Starts – What regulates the flow of huge ice streams
Iceberg B-9 was an iceberg that calved in 1987. The iceberg measured 154 kilometres long and 35 kilometres wide with a total area of 5,390 square kilometres, it is one of the longest icebergs recorded. The calving took place east of the calving site of Iceberg B-15 and carried away Little America V. Starting in October 1987, Iceberg B-9 drifted for 22 months and covered 2,000 kilometres on its journey. B-9 moved northwest for seven months before being drawn southward by a subsurface current that led to its colliding with the Ross Ice Shelf in August 1988, it made a 100-kilometre radius gyre before continuing its northwest drift. B-9 moved at an average speed of 2.5 kilometres per day over the continental shelf, as measured by NOAA-10 and DMSP satellite positions, the ARGOS data buoy positions. In early August 1989, B-9 broke into three large pieces north of Cape Adare; these pieces were B-9A, 56 by 35 kilometres, B-9B, 100 by 35 kilometres, B-9C, 28 by 13 kilometres. B-9B drifted toward the Mertz Glacier on the George V Coast, where it came to rest next to the glacier and remained there for eighteen years.
On February 12 or 13th 2010, Iceberg B-9B collided with the giant floating Mertz Glacier tongue and shaved off a new iceberg that measured 78 kilometres long and 39 kilometres wide. The two icebergs began drifting together about 100–150 kilometres off the eastern coast of Antarctica. By December 2011, Iceberg B-9B had made its way into Commonwealth Bay and had broken up into three major pieces, parts of which were frozen to the seabed; the huge iceberg prevented three tourist ships from reaching Antarctica to mark the centenary of the polar voyage of Australian explorer Douglas Mawson, who landed at Cape Denison on January 8, 1912 and constructed a complex of huts that remain standing to this day. The three tourist ships attempted to reach the cape but had to turn back due to unusually harsh conditions caused by B-9B's position in the bay. A spokeswoman from the Australian government's Antarctic division observed, "There unusual ice conditions... affecting all the tourist ships that are going down there because the tourist ships don't have ice-breaking capabilities, they don't have choppers, so their ability to get anywhere near the Mawson's huts area is stopped."
Iceberg B-9B could remain in Commonwealth Bay for the next decade. List of recorded icebergs by area National Geographic IFL Science