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Waw An Namus
Waw an Namus (also spelled Wau-en-Namus, ar, واو الناموس) is a volcano in Libya. Of either Pleistocene or Holocene age, it is located within the eastern Fezzan region. The origin of the volcanism there and at Al Haruj farther north is not clear. Radiometric dating has yielded an age of about 200,000 years, but other circumstantial evidence points to a formation of the volcano during Holocene or even historical times. Waw an Namus is characterized by a caldera surrounded by an apron of dark tephra, which has a notable colour contrast to the surrounding desert terrain of the Sahara. A smaller crater lies northwest of the Waw an Namus caldera. The caldera itself contains a scoria cone. Several small lakes and associated vegetation are located within the caldera. Name The volcano is also known as Uaw en Namus, Uau en Namus, Wau-en-Namus and Wau Sqair. It means "oasis of mosquitoes", a reference to the small lakes around it and the numerous mosquitoes that exist at Waw ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pleistocene
The Pleistocene ( , often referred to as the ''Ice age'') is the geological Epoch (geology), epoch that lasted from about 2,580,000 to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was finally confirmed in 2009 by the International Union of Geological Sciences, the cutoff of the Pleistocene and the preceding Pliocene was regarded as being 1.806 million years Before Present (BP). Publications from earlier years may use either definition of the period. The end of the Pleistocene corresponds with the end of the last glacial period and also with the end of the Paleolithic age used in archaeology. The name is a combination of Ancient Greek grc, label=none, πλεῖστος, pleīstos, most and grc, label=none, καινός, kainós (latinized as ), 'new'. At the end of the preceding Pliocene, the previously isolated North and South American continents were joined by the Isthmus of Panama, causing Great American Interchang ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sebha
Sabha, or Sebha ( ar, سبها, Sebhā), is an oasis city in southwestern Libya, approximately south of Tripoli. It was historically the capital of the Fezzan region and the Military Territory of Fezzan-Ghadames and is now capital of the Sabha District. Sabha Air Base, south of the city, is a Libyan Air Force installation that is home to multiple MiG-25 aircraft. Sabha was where the erstwhile ruler of Libya, Muammar Gaddafi, grew up and received secondary education and where he also later became involved in political activism. After the Libyan Civil War and the resultant instability in the country, Sabha reportedly grew in importance as a slave auctioning town. However, an investigation by the National Commission for Human Rights in Libya (NCHRL) revealed that while there was illegal slavery, reports were exaggerated, as slave auctions were rare and not made public. The city was seized by forces loyal to the Libyan National Army (LNA) and its leader Khalifa Haftar in January ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lapilli
Lapilli is a size classification of tephra, which is material that falls out of the air during a volcanic eruption or during some meteorite impacts. ''Lapilli'' (singular: ''lapillus'') is Latin for "little stones". By definition lapilli range from in diameter. A pyroclastic particle greater than 64 mm in diameter is known as a volcanic bomb when molten, or a volcanic block when solid. Pyroclastic material with particles less than 2 mm in diameter is referred to as volcanic ash. Formation Lapilli are spheroid-, teardrop-, dumbbell- or button-shaped droplets of molten or semi-molten lava ejected from a volcanic eruption that fall to earth while still at least partially molten. These granules are not accretionary, but instead the direct result of liquid rock cooling as it travels through the air. Lapilli tuffs are a very common form of volcanic rock typical of rhyolite, andesite and dacite pyroclastic eruptions, where thick layers of lapilli can be deposited during a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Volcanic Ash
Volcanic ash consists of fragments of rock, mineral crystals, and volcanic glass, created during volcano, volcanic eruptions and measuring less than 2 mm (0.079 inches) in diameter. The term volcanic ash is also often loosely used to refer to all explosive eruption products (correctly referred to as ''tephra''), including particles larger than 2 mm. Volcanic ash is formed during explosive volcanic eruptions when dissolved gases in magma expand and escape violently into the atmosphere. The force of the gases shatters the magma and propels it into the atmosphere where it solidifies into fragments of volcanic rock and glass. Ash is also produced when magma comes into contact with water during phreatomagmatic eruptions, causing the water to explosively flash to steam leading to shattering of magma. Once in the air, ash is transported by wind up to thousands of kilometres away. Due to its wide dispersal, ash can have a number of impacts on society, including animal a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Basalt
Basalt (; ) is an aphanite, aphanitic (fine-grained) extrusive igneous rock formed from the rapid cooling of low-viscosity lava rich in magnesium and iron (mafic lava) exposed at or very near the planetary surface, surface of a terrestrial planet, rocky planet or natural satellite, moon. More than 90% of all volcanic rock on Earth is basalt. Rapid-cooling, fine-grained basalt is chemically equivalent to slow-cooling, coarse-grained gabbro. The eruption of basalt lava is observed by geologists at about 20 volcanoes per year. Basalt is also an important rock type on other planetary bodies in the Solar System. For example, the bulk of the plains of volcanism on Venus, Venus, which cover ~80% of the surface, are basaltic; the lunar mare, lunar maria are plains of flood-basaltic lava flows; and basalt is a common rock on the surface of Mars. Molten basalt lava has a low viscosity due to its relatively low silica content (between 45% and 52%), resulting in rapidly moving lava flo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gullies
A gully is a landform created by running water, mass movement, or commonly a combination of both eroding sharply into soil or other relatively erodible material, typically on a hillside or in river floodplains or terraces. Gullies resemble large ditches or small valleys, but are metres to tens of metres in depth and width and are characterised by a distinct 'headscarp' or 'headwall' and progress by headward (i.e. upstream) erosion. Gullies are commonly related to intermittent or ephemeral water flow usually associated with localised intense or protracted rainfall events, or snowmelt. Gullies can be formed and accelerated by cultivation practices on hillslopes (often gentle gradient) in farmland, and they can develop rapidly in rangelands from existing natural erosion forms subject to vegetative cover removal and livestock activity. Etymology The earliest known usage of the term is from 1657. It originates from the French word ''goulet'', a diminutive form of ''goule'' which m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phreatomagmatic
Phreatomagmatic eruptions are volcanic eruptions resulting from interaction between magma and water. They differ from exclusively magmatic eruptions and phreatic eruptions. Unlike phreatic eruptions, the products of phreatomagmatic eruptions contain juvenile (magmatic) clasts.Heiken, G. & Wohletz, K. 1985. Volcanic Ash. University of California Press, Berkeley It is common for a large explosive eruption to have magmatic and phreatomagmatic components. Mechanisms Several competing theories exist as to the exact mechanism of ash formation. The most common is the theory of explosive thermal contraction of particles under rapid cooling from contact with water. In many cases the water is supplied by the sea, for example with Surtsey. In other cases the water may be present in a lake or caldera-lake, for example Santorini, where the phreatomagmatic component of the Minoan eruption was a result of both a lake and later the sea. There have also been examples of interaction between magma ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Reed (plant)
Reed is a common name for several tall, grass-like plants of wetlands. Varieties They are all members of the order Poales (in the modern, expanded circumscription), and include: In the grass family, Poaceae * Common reed (''Phragmites australis''), the original species named reed * Giant reed (''Arundo donax''), used for making reeds for musical instruments * Burma reed (''Neyraudia reynaudiana'') * Reed canary-grass (''Phalaris arundinacea'') * Reed sweet-grass (''Glyceria maxima'') * Small-reed (''Calamagrostis'' species) In the sedge family, Cyperaceae * Paper reed or papyrus ('' Cyperus papyrus''), the source of the Ancient Egyptian writing material, also used for making boats In the family Typhaceae * Bur-reed (''Sparganium'' species) * Reed-mace (''Typha'' species), also called bulrush or cattail In the family Restionaceae * Cape thatching reed ('' Elegia tectorum''), a restio originating from the South-western Cape, South Africa. * Thatching reed (''Thamnochortus ins ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dune
A dune is a landform composed of wind- or water-driven sand. It typically takes the form of a mound, ridge, or hill. An area with dunes is called a dune system or a dune complex. A large dune complex is called a dune field, while broad, flat regions covered with wind-swept sand or dunes with little or no vegetation are called ''ergs'' or ''sand seas''. Dunes occur in different shapes and sizes, but most kinds of dunes are longer on the stoss (upflow) side, where the sand is pushed up the dune, and have a shorter ''slip face'' in the lee side. The valley or trough between dunes is called a ''dune slack''. Dunes are most common in desert environments, where the lack of moisture hinders the growth of vegetation that would otherwise interfere with the development of dunes. However, sand deposits are not restricted to deserts, and dunes are also found along sea shores, along streams in semiarid climates, in areas of glacial outwash, and in other areas where poorly cemented sa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Degassing
Degassing, also known as degasification, is the removal of dissolved gases from liquids, especially water or aqueous solutions. There are numerous methods for removing gases from liquids. Gases are removed for various reasons. Chemists remove gases from solvents when the compounds they are working on are possibly air- or oxygen-sensitive (air-free technique), or when bubble formation at solid-liquid interfaces becomes a problem. The formation of gas bubbles when a liquid is frozen can also be undesirable, necessitating degassing beforehand. Pressure reduction The solubility of gas obeys Henry's law, that is, the amount of a dissolved gas in a liquid is proportional to its partial pressure. Therefore, placing a solution under reduced pressure makes the dissolved gas less soluble. Sonication and stirring under reduced pressure can usually enhance the efficiency. This technique is often referred to as ''vacuum degasification''. Specialized vacuum chambers, called vacuum degassers, ar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phreatic Eruption
A phreatic eruption, also called a phreatic explosion, ultravulcanian eruption or steam-blast eruption, occurs when magma heats ground water or surface water. The extreme temperature of the magma (anywhere from ) causes near-instantaneous evaporation of water to steam, resulting in an explosion of steam, water, ash, rock, and volcanic bombs. At Mount St. Helens in Washington state, hundreds of steam explosions preceded the 1980 Plinian eruption of the volcano. A less intense geothermal event may result in a mud volcano. Phreatic eruptions typically include steam and rock fragments; the inclusion of liquid lava is unusual. The temperature of the fragments can range from cold to incandescent. If molten magma is included, volcanologists classify the event as a phreatomagmatic eruption. These eruptions occasionally create broad, low-relief craters called '' maars''. Phreatic explosions can be accompanied by carbon dioxide or hydrogen sulfide gas-emissions. Carbon dioxide c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Libyan Civil War
Demographics of Libya is the demography of Libya, specifically covering population density, ethnicity, education level, health of the populace, economic status, and religious affiliations, as well as other aspects of the Libyan population. The Libyan population resides in the country of Libya, a territory located on the Mediterranean coast of North Africa, to the west of and adjacent to Egypt. Libyans live in Tripoli. It is the capital of the country and first in terms of urban population, as well as Benghazi, Libya's second largest city. History Historically Berber, over the centuries, Libya has been occupied by the Phoenicians, Greeks, Romans, Arabs, and Italians. The Phoenicians had a big impact on Libya. Many of the coastal towns and cities of Libya were founded by the Phoenicians as trade outposts within the southern Mediterranean coast in order to facilitate the Phoenician business activities in the area. Starting in the 8th century BC, Libya was under the rule of th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
