The Pliocene Epoch is the epoch in the geologic timescale that extends from 5.333 million to 2.58 million years BP. It is the second and youngest epoch of the Neogene Period in the Cenozoic Era, the Pliocene follows the Miocene Epoch and is followed by the Pleistocene Epoch.588 to 1.806 million years ago, and is now included in the Pleistocene. As with other geologic periods, the geological strata that define the start and end are well identified but the exact dates of the start. The boundaries defining the Pliocene are not set at an easily identified worldwide event, the upper boundary was set at the start of the Pleistocene glaciations. The Pliocene was named by Sir Charles Lyell, the name comes from the Greek words πλεῖον and καινός and means roughly continuation of the recent, referring to the essentially modern marine mollusc faunas. H. W. Fowler called the term a regrettable barbarism, in the official timescale of the ICS, the Pliocene is subdivided into two stages. From youngest to oldest they are, Piacenzian Zanclean The Piacenzian is sometimes referred to as the Late Pliocene, in the system of North American Land Mammal Ages include Hemphillian, and Blancan.
The Blancan extends forward into the Pleistocene, South American Land Mammal Ages include Montehermosan and Uquian. In the Paratethys area the Pliocene contains the Dacian and Romanian stages, as usual in stratigraphy, there are many other regional and local subdivisions in use. In Britain the Pliocene is divided into the stages, Waltonian, Pre-Ludhamian, Thurnian, Bramertonian or Antian, Pre-Pastonian or Baventian and Beestonian. The exact correlations between these stages and the ICS stages is still a matter of detail. The formation of an Arctic ice cap is signaled by a shift in oxygen isotope ratios and ice-rafted cobbles in the North Atlantic. Mid-latitude glaciation was probably underway before the end of the epoch, the global cooling that occurred during the Pliocene may have spurred on the disappearance of forests and the spread of grasslands and savannas. Continents continued to drift, moving from positions possibly as far as 250 km from their present locations to positions only 70 km from their current locations, africas collision with Europe formed the Mediterranean Sea, cutting off the remnants of the Tethys Ocean.
The border between the Miocene and the Pliocene is the time of the Messinian salinity crisis, Sea level changes exposed the land-bridge between Alaska and Asia. Pliocene marine rocks are exposed in the Mediterranean, India. Elsewhere, they are exposed largely near shores, the change to a cooler, seasonal climate had considerable impacts on Pliocene vegetation, reducing tropical species worldwide. Deciduous forests proliferated, coniferous forests and tundra covered much of the north, tropical forests were limited to a tight band around the equator, and in addition to dry savannahs, deserts appeared in Asia and Africa
A summit is a point on a surface that is higher in elevation than all points immediately adjacent to it. Mathematically, a summit is a maximum in elevation. The topographic terms acme, apex and zenith are synonymous, the UIAA definition is that a summit is independent if it has a prominence of 30 metres or more, it is a mountain if it has a prominence of at least 300 metres. This can be summarised as follows, A pyramidal peak is an exaggerated form produced by ice erosion of a mountain top, Summit may refer to the highest point along a line, trail, or route. In many parts of the western United States, the term refers to the highest point along a road, highway. For example, the highest point along Interstate 80 in California is referred to as Donner Summit while the highest point on Interstate 5 is Siskiyou Mountain Summit, geoid Hill List of highest mountains Maxima and minima Nadir Summit accordance Peak finder
American Geophysical Union
The American Geophysical Union is a 501 nonprofit organization of geophysicists, consisting of over 62,000 members from 144 countries. AGUs activities are focused on the organization and dissemination of information in the interdisciplinary. The geophysical sciences involve four fundamental areas and ocean sciences, solid-Earth sciences, hydrologic sciences, the organizations headquarters is located on Florida Avenue in Washington, D. C. For more than 50 years, it operated as an affiliate of the National Academy of Sciences. On June 29,1972, AGU was incorporated in the District of Columbia, the AGU was intended to promote pure geophysics, exploration geophysics has its own society, the Society of Exploration Geophysicists. In a March 1919 report by a committee chaired by Robert S, the AGU was organized under seven sections, Seismology, Terrestrial magnetism and electricity, Oceanography and Geophysical chemistry. Hydrology was added in 1930 and Tectonophysics in 1940, in suggesting the latter name, Norman Bowen evoked a familiar theme, to designate this new borderline field between geophysics and geology. for the solution of problems of tectonics.
The first meeting of the AGU took place on April 23,1920, up to 1930, the number of members was restricted and members were elected. In 1932 the first annual dues US$2 were imposed, the membership grew to 4600 in 1950,13,000 in 1980, and 26,000 in 1990. As of 2013, it had 62,000 members from 144 countries, AGU publishes the weekly Eos newspaper and nineteen peer-reviewed scientific journals, The journal Radio Science is co-sponsored by the International Union of Radio Science. The journal Earth Interactions is published in partnership with the American Meteorological Society, in addition, International Journal of Geomagnetism and Aeronomy is no longer published and AGU distributes Chinese Journal of Geophysics and Nonlinear Processes in Geophysics. Many of the journals have high impact factors, with Paleoceanography having the highest within paleontology and Reviews of Geophysics the second highest within geochemistry, AGU has been publishing books for more than 85 years. AGU co-published its first electronic journal, Earth Interactions, in 1997 and it started its own electronic journal, Geophysics, Geosystems, in December 1999.
It made a transition to electronic publishing in 2001. For all its journals, the version became the publication of record. This was accompanied by a new scheme for articles that entirely did away with sequential page numbers. Instead, each article had a digital object identifier, as an example,10. 1029/2001GL014304 consists of the publisher identifier, the year, the journal code, and an article number. This new system was met with complaints from libraries and scientists, the article numbers provided no clue for libraries to find an article in printed versions, and even scientific databases were not set up to handle DOIs
An ultra-prominent peak, or Ultra for short, is defined as a mountain summit with a topographic prominence of 1,500 metres or more. There are approximately 1,524 such peaks on Earth, some peaks, such as the Matterhorn and Eiger, are not Ultras because they are connected to higher mountains by high cols and therefore do not achieve enough topographic prominence. The term Ultra is due to earth scientist Stephen Fry, from his studies of the prominence of peaks in Washington in the 1980s and his original term was ultra major mountain, referring to peaks with at least 5,000 ft of prominence. Currently,1,515 Ultras have been identified worldwide,637 in Asia,355 in North America,209 in South America,119 in Europe,84 in Africa,69 in Australasia and 39 in Antarctica. Many of the worlds largest mountains are Ultras, including Mount Everest, K2, Mont Blanc, on the other hand, others such as the Eiger and the Matterhorn are not Ultras because they do not have sufficient prominence. In British Columbia, some of the mountains listed do not even have generally recognized names, a number of Ultras have yet to be climbed, with Sauyr Zhotasy, Mount Siple, and Gangkar Puensum being the most likely candidates for the most prominent unclimbed mountain in the world.
All of the Seven Summits are Ultras by virtue of the fact that they are the points of large landmasses. Each has its key col at or near sea level, resulting in a value almost equal to its elevation. List of peaks by prominence gives the 125 most prominent peaks worldwide
Ross Ice Shelf
The Ross Ice Shelf is the largest ice shelf of Antarctica. It is several hundred metres thick, the nearly vertical ice front to the open sea is more than 600 kilometres long, and between 15 and 50 metres high above the water surface. Ninety percent of the ice, however, is below the water surface. Most of Ross Ice Shelf is in the Ross Dependency claimed by New Zealand and it floats in, and covers, a large southern portion of the Ross Sea and the entire Roosevelt Island located in the west of the Ross Sea. The ice shelf is named after Captain Sir James Clark Ross and it was originally called The Barrier, with various adjectives including Great Ice Barrier, as it prevented sailing further south. Ross mapped the ice front eastward to 160°W, in 1947, the US Board on Geographic Names applied the name Ross Shelf Ice to this feature and published it in the original US Antarctic Gazetteer. In January 1953 the name was changed to Ross Ice Shelf, four days later, they found their way into open water and were hoping that they would have a clear passage to their destination.
But on 11 January, the men were faced with a mass of ice. Sir James Clark Ross, who was the commander, Well. Two volcanoes in the region were named by Ross for his vessels, for early Antarctic explorers seeking to reach the South Pole, the Ross Ice Shelf became a starting area. The findings were presented at a lecture entitled Universitas Antarctica, given 7 June 1911 and were published in the account of Scotts second expedition. Both Roald Amundsen and Scott crossed the shelf to reach the Pole in 1911, Amundsen wrote, Along its outer edge the Barrier shows an even, flat surface, but here, inside the bay, the conditions were entirely different. Even from the deck of the Fram we were able to observe great disturbances of the surface in every direction, the greatest elevation lay to the south in the form of a lofty, arched ridge, which we took to be about 500 feet high on the horizon. But it might be assumed that this continued to rise beyond the range of vision. The next day, the party made its first steps on the Barrier, after half an hour’s march we were already at the first important point—the connection between the sea-ice and the Barrier.
This connection had always haunted our brains, a high, perpendicular face of ice, up which we should have to haul our things laboriously with the help of tackles. Or a great and dangerous fissure, which we should not be able to cross without going a long way round and we naturally expected something of the sort. This mighty and terrible monster would, of course, offer resistance in form or other
The Pleistocene is the geological epoch which lasted from about 2,588,000 to 11,700 years ago, spanning the worlds most recent period of repeated glaciations. The end of the Pleistocene corresponds with the end of the last glacial period, the Pleistocene is the first epoch of the Quaternary Period or sixth epoch of the Cenozoic Era. In the ICS timescale, the Pleistocene is divided into four stages or ages, all of these stages were defined in southern Europe. In addition to this subdivision, various regional subdivisions are often used. Charles Lyell introduced the term pleistocene in 1839 to describe strata in Sicily that had at least 70% of their molluscan fauna still living today and this distinguished it from the older Pliocene Epoch, which Lyell had originally thought to be the youngest fossil rock layer. The Pleistocene has been dated from 2.588 million to 11,700 years before present and it covers most of the latest period of repeated glaciation, up to and including the Younger Dryas cold spell.
The end of the Younger Dryas has been dated to about 9640 BC, the IUGS has yet to approve a type section, Global Boundary Stratotype Section and Point, for the upper Pleistocene/Holocene boundary. The proposed section is the North Greenland Ice Core Project ice core 75°06 N 42°18 W, the lower boundary of the Pleistocene Series is formally defined magnetostratigraphically as the base of the Matuyama chronozone, isotopic stage 103. Above this point there are notable extinctions of the calcareous nanofossils, Discoaster pentaradiatus, the Pleistocene covers the recent period of repeated glaciations. The name Plio-Pleistocene has, in the past, been used to mean the last ice age. The revised definition of the Quaternary, by pushing back the date of the Pleistocene to 2.58 Ma. Pleistocene climate was marked by repeated glacial cycles in which continental glaciers pushed to the 40th parallel in some places and it is estimated that, at maximum glacial extent, 30% of the Earths surface was covered by ice.
In addition, a zone of permafrost stretched southward from the edge of the sheet, a few hundred kilometres in North America. The mean annual temperature at the edge of the ice was −6 °C, during interglacial times, such as at present, drowned coastlines were common, mitigated by isostatic or other emergent motion of some regions. The effects of glaciation were global, antarctica was ice-bound throughout the Pleistocene as well as the preceding Pliocene. The Andes were covered in the south by the Patagonian ice cap, there were glaciers in New Zealand and Tasmania. The current decaying glaciers of Mount Kenya, Mount Kilimanjaro, glaciers existed in the mountains of Ethiopia and to the west in the Atlas mountains. In the northern hemisphere, many glaciers fused into one, the Cordilleran ice sheet covered the North American northwest, the east was covered by the Laurentide
It contains the geographic South Pole and is situated in the Antarctic region of the Southern Hemisphere, almost entirely south of the Antarctic Circle, and is surrounded by the Southern Ocean. At 14,000,000 square kilometres, it is the fifth-largest continent, for comparison, Antarctica is nearly twice the size of Australia. About 98% of Antarctica is covered by ice that averages 1.9 km in thickness, Antarctica, on average, is the coldest and windiest continent, and has the highest average elevation of all the continents. Antarctica is a desert, with precipitation of only 200 mm along the coast. The temperature in Antarctica has reached −89.2 °C, though the average for the quarter is −63 °C. Anywhere from 1,000 to 5,000 people reside throughout the year at the research stations scattered across the continent. Organisms native to Antarctica include many types of algae, fungi, protista, where it occurs, is tundra. The continent, remained neglected for the rest of the 19th century because of its hostile environment, lack of easily accessible resources.
In 1895, the first confirmed landing was conducted by a team of Norwegians, Antarctica is a de facto condominium, governed by parties to the Antarctic Treaty System that have consulting status. Twelve countries signed the Antarctic Treaty in 1959, and thirty-eight have signed it since then, the treaty prohibits military activities and mineral mining, prohibits nuclear explosions and nuclear waste disposal, supports scientific research, and protects the continents ecozone. Ongoing experiments are conducted by more than 4,000 scientists from many nations, the name Antarctica is the romanised version of the Greek compound word ἀνταρκτική, feminine of ἀνταρκτικός, meaning opposite to the Arctic, opposite to the north. Aristotle wrote in his book Meteorology about an Antarctic region in c.350 B. C, marinus of Tyre reportedly used the name in his unpreserved world map from the 2nd century A. D. Before acquiring its present geographical connotations, the term was used for locations that could be defined as opposite to the north.
For example, the short-lived French colony established in Brazil in the 16th century was called France Antarctique, the first formal use of the name Antarctica as a continental name in the 1890s is attributed to the Scottish cartographer John George Bartholomew. Antarctica has no population and there is no evidence that it was seen by humans until the 19th century. Explorer Matthew Flinders, in particular, has credited with popularising the transfer of the name Terra Australis to Australia. Cook came within about 120 km of the Antarctic coast before retreating in the face of ice in January 1773. The first confirmed sighting of Antarctica can be narrowed down to the crews of ships captained by three individuals, according to various organisations, ships captained by three men sighted Antarctica or its ice shelf in 1820, von Bellingshausen, Edward Bransfield, and Nathaniel Palmer
McMurdo Sound and its ice-clogged waters extends about 55 kilometres long and wide. The sound connects the Ross Sea to the north with the Ross Ice Shelf cavity to the south via Haskell Strait, the strait is largely covered by the McMurdo Ice Shelf. The Royal Society Range rises from sea level to 4,205 metres on the western shoreline, Ross Island, an historic jumping-off point for polar explorers, designates the eastern boundary. The active volcano Mt Erebus at 3,794 metres dominates Ross Island, Antarcticas largest scientific base, the United States McMurdo Station, as well as the New Zealand Scott Base are on the southern shore of the island. Less than 10 percent of McMurdo Sounds shoreline is free of ice and it is the southernmost navigable body of water in the world. Captain James Clark Ross discovered this sound, which is about 1,300 kilometres from the South Pole, in February 1841, the sound today serves as a resupply route for cargo ships and for airplanes that land on the floating ice airstrips near the McMurdo Station.
However, McMurdo Station’s continuous occupation by human beings since 1957/58 has dirtied the harbor of Winter Quarters Bay, the pack ice that girdles the shoreline at Winter Quarters Bay and elsewhere in the sound presents a formidable obstacle to surface ships. Vessels require ice-strengthened hulls and often have to rely upon escort by icebreakers, such extreme sea conditions have limited access by tourists, who otherwise are appearing in increasing numbers in the open waters of the Antarctic Peninsula. The few tourists who reach the McMurdo Sound find spectacular scenery with wildlife to be seen, including whales, Adelie penguins. Cold circumpolar currents of the Southern Ocean reduce the flow of warm South Pacific or South Atlantic waters reaching McMurdo Sound, bitter katabatic winds spilling down from the Antarctic polar plateau into McMurdo Sound demonstrate Antarcticas status as the coldest and windiest continent in the world. The McMurdo Sound freezes over with sea ice about 3 metres thick during the winter, the Antarctic summer causes the pack ice to break up.
Wind and currents may push the ice northward into the Ross Sea, temperatures during the dark winter months at McMurdo Station have dropped as low as −51 °C. However and January are the warmest months, with highs at −1 °C. McMurdo Sounds role as a strategic waterway dates back to early 20th century Antarctic exploration, British explorers Ernest Shackleton and Robert Scott built bases on the sounds shoreline as jumping-off points for their overland expeditions to the South Pole. McMurdo Sounds logistic importance continues today, aircraft transporting cargo and passengers land upon frozen runways at Williams Field on the McMurdo Ice Shelf. Moreover, the annual sealift of a ship and fuel tanker rely upon the sound as a supply route to the continents largest base. Both the U. S. base and New Zealands nearby Scott Base are on the tip of Ross Island. Ross Island is the southmost piece of land in Antarctica that is accessible by ship, in addition, the harbor at McMurdos Winter Quarters Bay is the worlds southmost seaport
RRS Discovery was the last traditional wooden three-masted ship to be built in Britain. Designed for Antarctic research, it was launched as a Royal Research Ship in 1901 and it is now the centrepiece of visitor attraction in its home, Dundee. In charge of her design was W. E. Smith, one of the naval architects at the Admiralty, while the ships engine, boilers. The main compass was mounted amidships and there were to be no steel or iron fittings within 30 feet of this point. For the same reason the boiler and engines were mounted towards the stern of the ship, the yard was previously owned by Alexander Stephen and Sons and had built the Terra Nova in 1884. 1m in modern currency. At her economical cruising speed of 6 knots she only carried enough coal for 7700 miles of steaming, at 8 knots she could steam only 5100 miles. She was rigged as a barque and the total sail area was 12,296 square feet. Following the practice of the most modern sailing ships of the time, the ship was rigged to carry several large staysails and the funnel was hinged at the base so it could be laid on the deck when the large mizzen staysail was rigged once at sea.
At the time of her launch Discovery was widely held to be the strongest wooden ship ever built, the hull frames, placed much closer together than was normal, were made of solid sections of oak up to 11 inches thick. The outer hull was formed from two layers - one 6 inches thick and an outer skin some 5 inches thick, a third lining was laid inside the frames, forming a double bottom and skin around almost the entire hull. This meant that in places the hull was over 2 feet thick, providing not only formidable strength, the construction meant that it was impossible to install portholes so the crew relied on mushroom vents on the deck to allow air and light into the interior. The outer hull is made of English Elm and Greenheart, oak beams run across the hull forming three decks - the lower deck beams are 11 inches square in cross-section and are placed less than three feet apart along the ships length. Seven transverse bulkheads, of wood, provide additional strength, to prevent damage from ice floes or crushing the two-blade propeller could be hoisted out of the way and the rudder could be easily detached and stored aboard.
Iron-shod bows were severely raked so that when ramming the ice they would ride up over the margin, the coal bunkers on each side contained a steel tank, each of which could hold 60 tons of fresh water. On the long trip to and from New Zealand these tanks could hold additional coal. The metal tanks contributed to the strength of the hull around the boiler. She was launched into the Firth of Tay on 21 March 1901 by Lady Markham, the British National Antarctic Expedition departed the UK less than five months after the Discovery was launched and only a week after the ship left Dundee
Types of volcanic eruptions
Several types of volcanic eruptions—during which lava and assorted gases are expelled from a volcanic vent or fissure—have been distinguished by volcanologists. These are often named after famous volcanoes where that type of behavior has been observed, some volcanoes may exhibit only one characteristic type of eruption during a period of activity, while others may display an entire sequence of types all in one eruptive series. There are three different types of eruptions, the most well-observed are magmatic eruptions, which involve the decompression of gas within magma that propels it forward. Phreatomagmatic eruptions are another type of eruption, driven by the compression of gas within magma. Within these wide-defining eruptive types are several subtypes, the weakest are Hawaiian and submarine, followed by Vulcanian and Surtseyan. The stronger eruptive types are Pelean eruptions, followed by Plinian eruptions and phreatic eruptions are defined by their eruptive mechanism, and vary in strength.
An important measure of strength is Volcanic Explosivity Index, an order of magnitude scale ranging from 0 to 8 that often correlates to eruptive types. Explosive eruptions are characterized by gas-driven explosions that propels magma and tephra, effusive eruptions, are characterized by the outpouring of lava without significant explosive eruption. Volcanic eruptions vary widely in strength, on the one extreme there are effusive Hawaiian eruptions, which are characterized by lava fountains and fluid lava flows, which are typically not very dangerous. On the other extreme, Plinian eruptions are large, volcanoes are not bound to one eruptive style, and frequently display many different types, both passive and explosive, even the span of a single eruptive cycle. Volcanoes do not always erupt vertically from a crater near their peak. Some volcanoes exhibit lateral and fissure eruptions, many Hawaiian eruptions start from rift zones, and some of the strongest Surtseyan eruptions develop along fracture zones.
Scientists believed that pulses of magma mixed together in the chamber before climbing upward—a process estimated to several thousands of years. But Columbia University volcanologists found that the eruption of Costa Rica’s Irazú Volcano in 1963 was likely triggered by magma that took a route from the mantle over just a few months. The volcanic explosivity index is a scale, from 0 to 8 and it is used by the Smithsonian Institutions Global Volcanism Program in assessing the impact of historic and prehistoric lava flows. It operates in a way similar to the Richter scale for earthquakes, the vast majority of volcanic eruptions are of VEIs between 0 and 2. Volcanic eruptions by VEI index Magmatic eruptions produce juvenile clasts during explosive decompression from gas release, Hawaiian eruptions are a type of volcanic eruption, named after the Hawaiian volcanoes with which this eruptive type is hallmark. Hawaiian eruptions are the calmest types of events, characterized by the effusive eruption of very fluid basalt-type lavas with low gaseous content
A stratovolcano, known as a composite volcano, is a conical volcano built up by many layers of hardened lava, tephra and volcanic ash. Unlike shield volcanoes, stratovolcanoes are characterized by a profile and periodic explosive eruptions and effusive eruptions. The lava flowing from stratovolcanoes typically cools and hardens before spreading far due to high viscosity, the magma forming this lava is often felsic, having high-to-intermediate levels of silica, with lesser amounts of less-viscous mafic magma. Extensive felsic lava flows are uncommon, but have travelled as far as 15 km, stratovolcanoes are sometimes called composite volcanoes because of their composite layered structure built up from sequential outpourings of eruptive materials. They are among the most common types of volcanoes, in contrast to the less common shield volcanoes, two famous stratovolcanoes are Krakatoa, best known for its catastrophic eruption in 1883 and Vesuvius, famous for its destruction of the towns Pompeii and Herculaneum in 79 CE.
Both eruptions claimed thousands of lives, in modern times, Mount Saint Helens and Mount Pinatubo have erupted catastrophically. Existence of stratovolcanoes has not been proved on other bodies of the solar system with one exception. Their existence was suggested for some isolated massifs on Mars, e. g. Zephyria Tholus, stratovolcanoes are common at subduction zones, forming chains along plate tectonic boundaries where oceanic crust is drawn under continental crust or another oceanic plate. The release of water from hydrated minerals is termed dewatering, and occurs at pressures and temperatures for each mineral. The magma rises through the crust, incorporating silica-rich crustal rock, when the magma nears the top surface, it pools in a magma chamber under or within the volcano. There, the low pressure allows water and other volatiles dissolved in the magma to escape from solution, as occurs when a bottle of carbonated water is opened. Once a critical volume of magma and gas accumulates, the obstacle of the cone is overcome.
In recorded history, explosive eruptions at subduction zone volcanoes have posed the greatest hazard to civilizations. Subduction-zone stratovolcanoes, such as Mount St. Helens, Mount Etna and Mount Pinatubo, typically erupt with explosive force, as a consequence, the tremendous internal pressures of the trapped volcanic gases remain in the pasty magma. Following the breaching of the chamber, the magma degasses explosively. The gases and water out with speed and force. Since 1600 CE, nearly 300,000 people have killed by volcanic eruptions. Most deaths were caused by flows and mudflows, deadly hazards that often accompany explosive eruptions of subduction-zone stratovolcanoes
Mount Morning is a dome-shaped shield volcano standing WSW of Mount Discovery and east of Koettlitz Glacier in Victoria Land. Discovered by the British National Antarctic Expedition which named it for the Morning, Morning Glacier is a glacier named in association with Mount Morning. List of volcanoes in Antarctica LeMasurier, W. E. Thomson, volcanoes of the Antarctic Plate and Southern Oceans. Skiing the Pacific Ring of Fire and Beyond, amar Andalkars Ski Mountaineering and Climbing Site. U. S. Geological Survey Geographic Names Information System, Mount Morning GNIS entry for Mt. Morning Polar Discovery, Mount Morning Lava Flows