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Toba Catastrophe Theory
The Toba eruption (also called the Toba supereruption and the Youngest Toba eruption) was a supervolcanic eruption that occurred around 74,000 years ago, during the Late Pleistocene, at the site of present-day Lake Toba, in Sumatra, Indonesia. It was the last in a series of at least four caldera-forming eruptions there, the earlier known caldera having formed about 1.2 million years ago. This, the last eruption, had an estimated volcanic explosivity index of 8, making it the largest known explosive volcanic eruption in the Quaternary, and one of the largest known explosive eruptions in the Earth's history. Eruption Chronology of the Toba eruption The exact date of the eruption is unknown, but the pattern of ash deposits suggests that it occurred during the northern summer because only the summer monsoon could have deposited Toba ashfall in the South China Sea. The eruption lasted perhaps 9 to 14 days. The most recent two high-precision argon–argon datings dated the erupt ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sumatra
Sumatra () is one of the Sunda Islands of western Indonesia. It is the largest island that is fully within Indonesian territory, as well as the list of islands by area, sixth-largest island in the world at 482,286.55 km2 (182,812 mi.2), including adjacent islands such as the Simeulue Island, Simeulue, Nias Island, Nias, Mentawai Islands, Mentawai, Enggano Island, Enggano, Riau Islands, Bangka Belitung and Krakatoa archipelago. Sumatra is an elongated landmass spanning a diagonal northwest–southeast axis. The Indian Ocean borders the northwest, west, and southwest coasts of Sumatra, with the island chain of Simeulue, Nias, Mentawai Islands, Mentawai, and Enggano off the western coast. In the northeast, the narrow Strait of Malacca separates the island from the Malay Peninsula, which is an extension of the Eurasian continent. In the southeast, the narrow Sunda Strait, containing the Krakatoa archipelago, separates Sumatra from Java. The northern tip of Sumatra is near ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Argon–argon Dating
Argon–argon (or 40Ar/39Ar) dating is a radiometric dating method invented to supersede Potassium-argon dating, potassiumargon (K/Ar) dating in accuracy. The older method required splitting samples into two for separate potassium and argon measurements, while the newer method requires only one rock fragment or mineral grain and uses a single measurement of isotopes of argon, argon isotopes. 40Ar/39Ar dating relies on neutron irradiation from a nuclear reactor to convert a stable form of potassium (39K) into the radioactive 39Ar. As long as a standard of known age is co-irradiated with unknown samples, it is possible to use a single measurement of argon isotopes to calculate the 40K/40Ar* ratio, and thus to calculate the age of the unknown sample. 40Ar* refers to the radiogenic 40Ar, i.e. the 40Ar produced from radioactive decay of 40K. 40Ar* does not include atmospheric argon adsorbed to the surface or inherited through diffusion and its calculated value is derived from measuring t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sub-Saharan Africa
Sub-Saharan Africa is the area and regions of the continent of Africa that lie south of the Sahara. These include Central Africa, East Africa, Southern Africa, and West Africa. Geopolitically, in addition to the list of sovereign states and dependent territories in Africa, African countries and territories that are situated fully in that specified region, the term may also include polities that only have part of their territory located in that region, per the definition of the United Nations geoscheme for Africa, United Nations (UN). This is considered a non-standardised geographical region with the number of countries included varying from 46 to 48 depending on the organisation describing the region (e.g. United Nations, UN, World Health Organization, WHO, World Bank, etc.). The Regions of the African Union, African Union (AU) uses a different regional breakdown, recognising all 55 member states on the continent—grouping them into five distinct and standard regions. The te ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arabian Sea
The Arabian Sea () is a region of sea in the northern Indian Ocean, bounded on the west by the Arabian Peninsula, Gulf of Aden and Guardafui Channel, on the northwest by Gulf of Oman and Iran, on the north by Pakistan, on the east by India, and on the southeast by the Laccadive Sea and the Maldives, on the southwest by Somalia. Its total area is and its maximum depth is . The Gulf of Aden in the west connects the Arabian Sea to the Red Sea through the strait of Bab-el-Mandeb, and the Gulf of Oman is in the northwest, connecting it to the Persian Gulf. Geography The Arabian Sea's surface area is about .Arabian Sea Encyclopædia Britannica The maximum width of the sea is approximately , and its maximum depth is . The biggest river flowing into the sea is the Indus River. The Arabian Sea has two ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Strait Of Malacca
The Strait of Malacca is a narrow stretch of water, long and from wide, between the Malay Peninsula to the northeast and the Indonesian island of Sumatra to the southwest, connecting the Andaman Sea (Indian Ocean) and the South China Sea (Pacific Ocean). As the main shipping channel between the Indian and Pacific oceans, it is one of the most important shipping lanes in the world. Etymology The name "Malacca" is traditionally associated with the Malacca tree ('' Phyllanthus emblica''), also known as the Indian gooseberry tree, and is believed to derive from the local Malay word "Melaka". According to historical traditions, Parameswara, a Sumatran prince and the founder of the Malacca Sultanate, selected the site for his new kingdom where the city of Malacca now stands. It is said that he named the location "Melaka" after the Malacca tree under which he had rested. Over time, the name "Malacca" came to refer not only to the city but also to the strategically significant ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Indian Ocean
The Indian Ocean is the third-largest of the world's five oceanic divisions, covering or approximately 20% of the water area of Earth#Surface, Earth's surface. It is bounded by Asia to the north, Africa to the west and Australia (continent), Australia to the east. To the south it is bounded by the Southern Ocean or Antarctica, depending on the definition in use. The Indian Ocean has large marginal or regional seas, including the Andaman Sea, the Arabian Sea, the Bay of Bengal, and the Laccadive Sea. Geologically, the Indian Ocean is the youngest of the oceans, and it has distinct features such as narrow continental shelf, continental shelves. Its average depth is 3,741 m. It is the warmest ocean, with a significant impact on global climate due to its interaction with the atmosphere. Its waters are affected by the Indian Ocean Walker circulation, resulting in unique oceanic currents and upwelling patterns. The Indian Ocean is ecologically diverse, with important ecosystems such ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pyroclastic Flow
A pyroclastic flow (also known as a pyroclastic density current or a pyroclastic cloud) is a fast-moving current of hot gas and volcanic matter (collectively known as tephra) that flows along the ground away from a volcano at average speeds of but is capable of reaching speeds up to . The gases and tephra can reach temperatures of about . Pyroclastic flows are the deadliest of all volcanic hazards and are produced as a result of certain explosive eruptions; they normally touch the ground and hurtle downhill or spread laterally under gravity. Their speed depends upon the density of the current, the volcanic output rate, and the gradient of the slope. Origin of term The word ''pyroclast'' is derived from the Greek (''pýr''), meaning "fire", and (''klastós''), meaning "broken in pieces". A name for pyroclastic flows that glow red in the dark is (French, "burning cloud"); this was notably used to describe the disastrous 1902 eruption of Mount Pelée on Martinique, a Frenc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dense-rock Equivalent
Dense-rock equivalent (DRE) is a volcanologic calculation used to estimate volcanic eruption volume. One of the widely accepted measures of the size of a historic or prehistoric eruption is the volume of magma ejected as pumice and volcanic ash, known as tephra during an explosive phase of the eruption, or the volume of lava extruded during an effusive phase of a volcanic eruption. Eruption volumes are commonly expressed in cubic kilometers (km3). Historical and geological estimates of tephra volumes are usually obtained by mapping the distribution and thickness of tephra deposits on the ground after the eruption is over. For historical volcanic explosions, further estimates must be made of tephra deposits that might have changed significantly over time by other geological processes including erosion. Tephra volumes measured in this way must then be corrected for void spaces ( vesicles – bubbles within the pumice, empty spaces between individual pieces of pumice or ash) to get ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
USGS
The United States Geological Survey (USGS), founded as the Geological Survey, is an government agency, agency of the United States Department of the Interior, U.S. Department of the Interior whose work spans the disciplines of biology, geography, geology, and hydrology. The agency was founded on March 3, 1879, to study the landscape of the United States, its natural resources, and the natural hazards that threaten it. The agency also makes maps of planets and moons, based on data from List of NASA missions, U.S. space probes. The sole scientific agency of the U.S. Department of the Interior, USGS is a fact-finding research organization with no regulatory responsibility. It is headquartered in Reston, Virginia, with major offices near Lakewood, Colorado; at the Denver Federal Center; and in NASA Research Park in California. In 2009, it employed about 8,670 people. The current motto of the USGS, in use since August 1997, is "science for a changing world". The agency's previous s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Michigan Technological University
Michigan Technological University (Michigan Tech, MTU, or simply Tech) is a public research university in Houghton, Michigan, United States. It was founded in 1885 as the Michigan Mining School, the first post-secondary institution in the Upper Peninsula of Michigan. The university comprises five colleges and schools: the College of Engineering, the College of Computing, the College of Sciences and Arts, the College of Business, and the College of Forest Resources and Environmental Science. They offer more than 140 degree programs to nearly 7,000 graduate and undergraduate students. Its main campus sits on on a bluff overlooking Portage Lake. The campus consists of 36 buildings, the first of which was built in 1908. Michigan Tech's athletic teams are nicknamed the Huskies and compete primarily in the NCAA Division II Great Lakes Intercollegiate Athletic Conference (GLIAC). The men's hockey team competes in Division I as a member of the Central Collegiate Hockey Associ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
William I
William I may refer to: Kings * William the Conqueror (–1087), also known as William I, King of England * William I of Sicily (died 1166) * William I of Scotland (died 1214), known as William the Lion * William I of the Netherlands and Luxembourg (1772–1843) * William I of Bimbia () * William I of Württemberg (1781–1864) * William I, German Emperor (1797–1888) Nobles * William I of Gascony (died 848) * William I of Aquitaine (died 918) * William I of Montferrat () * William I of Normandy (–942) * William I of Montpellier () * William I of Provence (–993) * William I Talvas (–after 1030), seigneur of Alençon * William Iron Arm (before 1010–1046), Duke of Apulia * William I, Bishop of Utrecht (died 1076) * William I, Count of Nevers (–after 1083) * William I, Count of Burgundy (1020–1087) * William de Warenne, 1st Earl of Surrey (died 1088) * William I of Cerdanya (1068–1095) * William I of Bures (died 1142), French crusader * William I of Béar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ice Core
An ice core is a core sample that is typically removed from an ice sheet or a high mountain glacier A glacier (; or ) is a persistent body of dense ice, a form of rock, that is constantly moving downhill under its own weight. A glacier forms where the accumulation of snow exceeds its ablation over many years, often centuries. It acquires .... Since the ice forms from the incremental buildup of annual layers of snow, lower layers are older than upper ones, and an ice core contains ice formed over a range of years. Cores are Ice drilling, drilled with hand Auger (drill), augers (for shallow holes) or powered drills; they can reach depths of over two miles (3.2 km), and contain ice up to 800,000 years old. The physical properties of the ice and of material trapped in it can be used to reconstruct the climate over the age range of the core. The proportions of different oxygen and hydrogen isotopes provide information about Paleothermometer, ancient temperatures, a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
