Reginald Aldworth Daly
Reginald Aldworth Daly was a Canadian geologist. He was educated at the University of Toronto, where geologist A. P. Coleman persuaded him away from teaching mathematics and he attained his PhD at Harvard, and did postgraduate work in Germany and France. After working as a field geologist for the Canadian International Boundary Commission, he was a professor and he documented the geology alone, but had the help of one field assistant and numerous wranglers and porters. He collected 1,500 rock specimens and made 960 thin sections, the project included 1,300 photographs, dozens of lake soundings and structural mapping and morphology. In 1912, he filed his report with the Geological Survey of Canada. This work along the 49th parallel led him to formulate a theory of the origins of igneous rocks, according to Dalys biographer, James Natland, Daly was an early proponent of Arthur Holmes and Alfred Wegeners continental drift theory. Daly summarized his ideas in his 1926 book, Our Mobile Earth, Daly applied Newtonian physics to make his point, which was validated.
Daly was awarded the Penrose Medal in 1935, the Wollaston Medal in 1942, in 1950 he became foreign member of the Royal Netherlands Academy of Arts and Sciences. The mineral dalyite and craters on Mars and the Moon are named in his honor and his Cambridge, house is now a National Historic Landmark. 6, pp. 246–50, Bibcode, 1920PNAS.6. 246D, doi,10. 1073/pnas.6.5.246, PMC1084496, PMID16586806 Daly, R A, Low-Temperature Formation of Alkaline Feldspars in Limestones, Proc. 3, pp. 659–65, Bibcode, 1917PNAS.3. 659D, doi,10. 1073/pnas.3.11.659, PMC1091350, PMID16576265 Daly, R A, A New Test of the Subsidence Theory of Coral Reefs, Proc. Robert M. Hazen, Reginald Aldworth Daly, daly′s Biography, American Geophysical Union James H. Natland, Reginald Aldworth Daly, Eclectic Theoretician of the Earth. 2,2006 Francis Birch, Reginald Aldworth Daly, 1871-1957, A Biographical Memoir National Academy of Sciences, Washington, DC,36 pp.1960 Works by or about Reginald Aldworth Daly at Internet Archive
Journal of Geophysical Research
The Journal of Geophysical Research is a peer-reviewed scientific journal. It is the journal of the American Geophysical Union. It contains original research on the physical and biological processes that contribute to the understanding of the Earth, Sun and it has seven sections, A, B, C, D, E, F, and G. All current and back issues are available online for subscribers, the journal was originally named Terrestrial Magnetism by the American Geophysical Unions president Louis Agricola Bauer in 1896. It was entitled Terrestrial Magnetism and Atmospheric Electricity from 1899–1948, in 1980, three specialized sections were established, A, Space Physics, B, Solid Earth, and C, Oceans. Subsequently, further sections have been added, D, Atmospheres in 1984, E, Planets in 1991, F, Earth Surface in 2003, C, Oceans covers physical and chemical oceanography. D, Atmospheres covers atmospheric properties and processes, including the interaction of the atmosphere with other components of the Earth system, studies of the Earth are included when they concern exogenic effects or the comparison of the Earth to other planets.
G, Biogeosciences focuses on the interface between biology and the geosciences and attempts to understand the functions of the Earth system across multiple spatial and temporal scales. Each of the sections has one or more editors who are appointed by, each editor can in turn appoint associate editors. According to the Editor-in-Chief of JGR-Space Physics, With the switch to Wiley and this means that in a couple of years, each section of JGR will have its own Impact Factor. The journal is indexed by GEOBASE, GeoRef, PubMed, Web of Science and it published 2995 articles in 2010. According to the Journal Citation Reports, the journal has a 2010 impact factor of 3.303, ranking it 15th out of 165 journals in the category Geosciences, Journal of Geophysical Research—Atmospheres was the 6th most cited publication on climate change between 1999 and 2009. Among the most highly cited papers in the Journal of Geophysical Research are, Cande, D. V. Kent, revised calibration of the geomagnetic polarity timescale for the Late Cretaceous and Cenozoic.
Brune, J. N. Tectonic stress and the spectra of seismic shear Waves from earthquakes, analysis of variation of ocean-floor bathymetry and heat-flow with age. Jordan, T. H. Present-day plate motions, a global model of natural volatile organic compound emissions. CS1 maint, Uses authors parameter Kennel, C. F. Petschek, limit on stably trapped particle fluxes. Elasticity and constitution of the Earth interior, list of scientific journals in earth and atmospheric sciences Official website
Kola Superdeep Borehole
The Kola Superdeep Borehole is the result of a scientific drilling project of the Soviet Union in the Pechengsky District, on the Kola Peninsula. The project attempted to drill as deep as possible into the Earths crust, Drilling began on 24 May 1970 using the Uralmash-4E, and the Uralmash-15000 series drilling rig. Boreholes were drilled by branching from a central hole, the deepest, SG-3, reached 12,262 metres in 1989 and still is the deepest artificial point on Earth. In terms of depth, it is the deepest borehole in the world. The borehole is 9 inches in diameter, the main target depth was set at 15,000 m. On 6 June 1979, the depth record held by the Bertha Rogers hole in Washita County, United States. In 1983, the drill passed 12,000 m, and drilling was stopped for about a year for numerous scientific and celebratory visits to the site. This idle period may have contributed to a breakdown on 27 September 1984, after drilling to 12,066 m, Drilling was restarted from 7,000 m. The hole reached 12,262 m in 1989, in that year, the hole depth was expected to reach 13,500 m by the end of 1990 and 15,000 m by 1993.
However, because of higher-than-expected temperatures at depth and location,180 °C instead of expected 100 °C, drilling deeper was deemed unfeasible. With the projected increase in temperature with increasing depth, drilling to 15,000 m would have meant working at a temperature of 300 °C. The Kola borehole penetrated about a third of the way through the Baltic continental crust, estimated to be around 35 kilometres deep, the project has been a site of extensive geophysical studies. Instead the change in the wave velocity is caused by a metamorphic transition in the granite rock. In addition, the rock at that depth had been fractured and was saturated with water. This water, unlike water, must have come from deep-crust minerals and had been unable to reach the surface because of a layer of impermeable rock. Another unexpected discovery was a quantity of hydrogen gas, the mud that flowed out of the hole was described as boiling with hydrogen. The project was closed down in late 2006 because of a lack of funding, all the drilling and research equipment was scrapped.
The site has been abandoned since 2008, the United States had embarked on a similar project in 1957, dubbed Project Mohole, which was intended to penetrate the shallow crust under the Pacific Ocean off Mexico
Ancient Greek includes the forms of Greek used in ancient Greece and the ancient world from around the 9th century BC to the 6th century AD. It is often divided into the Archaic period, Classical period. It is antedated in the second millennium BC by Mycenaean Greek, the language of the Hellenistic phase is known as Koine. Koine is regarded as a historical stage of its own, although in its earliest form it closely resembled Attic Greek. Prior to the Koine period, Greek of the classic and earlier periods included several regional dialects, Ancient Greek was the language of Homer and of fifth-century Athenian historians and philosophers. It has contributed many words to English vocabulary and has been a subject of study in educational institutions of the Western world since the Renaissance. This article primarily contains information about the Epic and Classical phases of the language, Ancient Greek was a pluricentric language, divided into many dialects. The main dialect groups are Attic and Ionic, Arcadocypriot, some dialects are found in standardized literary forms used in literature, while others are attested only in inscriptions.
There are several historical forms, homeric Greek is a literary form of Archaic Greek used in the epic poems, the Iliad and Odyssey, and in poems by other authors. Homeric Greek had significant differences in grammar and pronunciation from Classical Attic, the origins, early form and development of the Hellenic language family are not well understood because of a lack of contemporaneous evidence. Several theories exist about what Hellenic dialect groups may have existed between the divergence of early Greek-like speech from the common Proto-Indo-European language and the Classical period and they have the same general outline, but differ in some of the detail. The invasion would not be Dorian unless the invaders had some relationship to the historical Dorians. The invasion is known to have displaced population to the Attic-Ionic regions, the Greeks of this period believed there were three major divisions of all Greek people—Dorians and Ionians, each with their own defining and distinctive dialects.
Often non-west is called East Greek, Arcadocypriot apparently descended more closely from the Mycenaean Greek of the Bronze Age. Boeotian had come under a strong Northwest Greek influence, and can in some respects be considered a transitional dialect, thessalian likewise had come under Northwest Greek influence, though to a lesser degree. Most of the dialect sub-groups listed above had further subdivisions, generally equivalent to a city-state and its surrounding territory, Doric notably had several intermediate divisions as well, into Island Doric, Southern Peloponnesus Doric, and Northern Peloponnesus Doric. The Lesbian dialect was Aeolic Greek and this dialect slowly replaced most of the older dialects, although Doric dialect has survived in the Tsakonian language, which is spoken in the region of modern Sparta. Doric has passed down its aorist terminations into most verbs of Demotic Greek, by about the 6th century AD, the Koine had slowly metamorphosized into Medieval Greek
The theoretical model builds on the concept of continental drift developed during the first few decades of the 20th century. The geoscientific community accepted plate-tectonic theory after seafloor spreading was validated in the late 1950s, the lithosphere, which is the rigid outermost shell of a planet, is broken up into tectonic plates. The Earths lithosphere is composed of seven or eight major plates, where the plates meet, their relative motion determines the type of boundary, divergent, or transform. Earthquakes, volcanic activity, mountain-building, and oceanic trench formation occur along plate boundaries. The relative movement of the plates typically ranges from zero to 100 mm annually, tectonic plates are composed of oceanic lithosphere and thicker continental lithosphere, each topped by its own kind of crust. Along convergent boundaries, subduction carries plates into the mantle, the material lost is balanced by the formation of new crust along divergent margins by seafloor spreading.
In this way, the surface of the lithosphere remains the same. This prediction of plate tectonics is referred to as the conveyor belt principle, earlier theories, since disproven, proposed gradual shrinking or gradual expansion of the globe. Tectonic plates are able to move because the Earths lithosphere has greater strength than the underlying asthenosphere. Lateral density variations in the result in convection. Plate movement is thought to be driven by a combination of the motion of the seafloor away from the ridge and drag, with downward suction. Another explanation lies in the different forces generated by forces of the Sun. The relative importance of each of these factors and their relationship to other is unclear. The outer layers of the Earth are divided into the lithosphere and asthenosphere and this is based on differences in mechanical properties and in the method for the transfer of heat. Mechanically, the lithosphere is cooler and more rigid, while the asthenosphere is hotter, in terms of heat transfer, the lithosphere loses heat by conduction, whereas the asthenosphere transfers heat by convection and has a nearly adiabatic temperature gradient.
The key principle of plate tectonics is that the lithosphere exists as separate and distinct tectonic plates, Plate motions range up to a typical 10–40 mm/year, to about 160 mm/year. The driving mechanism behind this movement is described below, tectonic lithosphere plates consist of lithospheric mantle overlain by either or both of two types of crustal material, oceanic crust and continental crust. Average oceanic lithosphere is typically 100 km thick, its thickness is a function of its age, as passes, it conductively cools
The mineral olivine is a magnesium iron silicate with the formula 2SiO4. Thus it is a type of nesosilicate or orthosilicate and it is a common mineral in the Earths subsurface but weathers quickly on the surface. The ratio of magnesium and iron varies between the two endmembers of the solid solution series and fayalite, compositions of olivine are commonly expressed as molar percentages of forsterite and fayalite. Forsterite has a high melting temperature at atmospheric pressure, almost 1,900 °C. The melting temperature varies smoothly between the two endmembers, as do other properties, olivine incorporates only minor amounts of elements other than oxygen, silicon and iron. Manganese and nickel commonly are the elements present in highest concentrations. Olivine gives its name to the group of minerals with a structure which includes tephroite and kirschsteinite. It has a structure similar to magnetite but uses one quadravalent. Olivine gemstones are called peridot and chrysolite, olivine is named for its typically olive-green color, though it may alter to a reddish color from the oxidation of iron.
Translucent olivine is sometimes used as a gemstone called peridot, some of the finest gem-quality olivine has been obtained from a body of mantle rocks on Zabargad island in the Red Sea. Olivine occurs in mafic and ultramafic igneous rocks and as a primary mineral in certain metamorphic rocks. Mg-rich olivine crystallizes from magma that is rich in magnesium and low in silica and that magma crystallizes to mafic rocks such as gabbro and basalt. Ultramafic rocks such as peridotite and dunite can be left after extraction of magmas. Olivine and high pressure structural variants constitute over 50% of the Earths upper mantle, the metamorphism of impure dolomite or other sedimentary rocks with high magnesium and low silica content produces Mg-rich olivine, or forsterite. In contrast, Mg-rich olivine does not occur stably with silica minerals, Mg-rich olivine is stable to pressures equivalent to a depth of about 410 km within Earth. Mg-rich olivine has discovered in meteorites, on the Moon and Mars, falling into infant stars.
Such meteorites include chondrites, collections of debris from the early Solar System, the spectral signature of olivine has been seen in the dust disks around young stars. The tails of comets often have the signature of olivine
A natural satellite or moon is, in the most common usage, an astronomical body that orbits a planet or minor planet. In the Solar System there are six planetary satellite systems containing 178 known natural satellites, four IAU-listed dwarf planets are known to have natural satellites, Haumea and Eris. As of January 2012, over 200 minor-planet moons have been discovered, the Earth–Moon system is unique in that the ratio of the mass of the Moon to the mass of Earth is much greater than that of any other natural-satellite–planet ratio in the Solar System. At 3,474 km across, Earths Moon is 0.27 times the diameter of Earth, the first known natural satellite was the Moon, but it was considered a planet until Copernicus introduction of heliocentrism in 1543. Until the discovery of the Galilean satellites in 1610, galileo chose to refer to his discoveries as Planetæ, but discoverers chose other terms to distinguish them from the objects they orbited. The first to use of the satellite to describe orbiting bodies was the German astronomer Johannes Kepler in his pamphlet Narratio de Observatis a se quatuor Iouis satellitibus erronibus in 1610.
He derived the term from the Latin word satelles, meaning guard, attendant, or companion, the term satellite thus became the normal one for referring to an object orbiting a planet, as it avoided the ambiguity of moon. In 1957, the launching of the artificial object Sputnik created a need for new terminology, to further avoid ambiguity, the convention is to capitalize the word Moon when referring to Earths natural satellite, but not when referring to other natural satellites. A few recent authors define moon as a satellite of a planet or minor planet, there is no established lower limit on what is considered a moon. Small asteroid moons, such as Dactyl, have been called moonlets, the upper limit is vague. Two orbiting bodies are described as a double body rather than primary. Asteroids such as 90 Antiope are considered double asteroids, but they have not forced a clear definition of what constitutes a moon, some authors consider the Pluto–Charon system to be a double planet. In contrast, irregular satellites are thought to be captured asteroids possibly further fragmented by collisions, most of the major natural satellites of the Solar System have regular orbits, while most of the small natural satellites have irregular orbits.
The Moon and possibly Charon are exceptions among large bodies in that they are thought to have originated by the collision of two large proto-planetary objects. The material that would have placed in orbit around the central body is predicted to have reaccreted to form one or more orbiting natural satellites. As opposed to planetary-sized bodies, asteroid moons are thought to form by this process. Triton is another exception, although large and in a close, circular orbit, its motion is retrograde, most regular moons in the Solar System are tidally locked to their respective primaries, meaning that the same side of the natural satellite always faces its planet. The only known exception is Saturns natural satellite Hyperion, which rotates chaotically because of the influence of Titan
A xenolith is a rock fragment which becomes enveloped in a larger rock during the latters development and solidification. In geology, the term xenolith is almost exclusively used to describe inclusions in igneous rock during magma emplacement, a xenocryst is an individual foreign crystal included within an igneous body. Examples of xenocrysts are quartz crystals in a silica-deficient lava and diamonds within kimberlite diatremes, although the term xenolith is most commonly associated with igneous inclusions, a broad definition could include rock fragments which have become encased in sedimentary rock. Xenoliths are sometimes found in recovered meteorites and xenocrysts provide important information about the composition of the otherwise inaccessible mantle. Basalts, kimberlites and lamprophyres, which have their source in the mantle, often contain fragments. Xenoliths of dunite and spinel lherzolite in basaltic lava flows are one example, kimberlites contain, in addition to diamond xenocrysts, fragments of lherzolites of varying composition.
The aluminium-bearing minerals of these fragments provide clues to the depth of origin, calcic plagioclase is stable to a depth of 25 km. Between 25 km and about 60 km, spinel is the stable aluminium phase, at depths greater than about 60 km, dense garnet becomes the aluminium-bearing mineral. Some kimberlites contain xenoliths of eclogite, which is considered to be the high-pressure metamorphic product of basaltic oceanic crust, the large-scale inclusion of foreign rock strata at the margins of an igneous intrusion is called a roof pendant. Blatt and Robert J. Tracy
The hydrosphere is the combined mass of water found on, and above the surface of a planet, minor planet or natural satellite. It has been estimated there are 1386 million cubic kilometers of water on Earth. This includes water in liquid and frozen forms in groundwater, lakes, saltwater accounts for 97. 5% of this amount. Fresh water accounts for only 2. 5%, of this fresh water,68. 9% is in the form of ice and permanent snow cover in the Arctic, the Antarctic, and mountain glaciers. 30. 8% is in the form of fresh groundwater, only 0. 3% of the fresh water on Earth is in easily accessible lakes and river systems. The total mass of the Earths hydrosphere is about 1.4 ×1018 tonnes, about 20 ×1012 tonnes of this is in Earths atmosphere. Approximately 75% of Earths surface, an area of some 361 million square kilometers, is covered by ocean, the average salinity of Earths oceans is about 35 grams of salt per kilogram of sea water. The hydrological cycle transfers water from one state or reservoir to another, reservoirs include atmospheric moisture, oceans, lakes, subterranean aquifers, polar icecaps and saturated soil.
Solar energy, in the form of heat and light, most evaporation comes from the oceans and is returned to the earth as snow or rain. Sublimation refers to evaporation from snow and ice, transpiration refers to the expiration of water through the minute pores or stomata of trees. Evapotranspiration is the used by hydrologists in reference to the three processes together, transpiration and evaporation. In his book Water, Marq de Villiers described the hydrosphere as a system in which water exists. The hydrosphere is intricate, interdependent, all-pervading and stable, de Villiers claimed that, On earth, the total amount of water has almost certainly not changed since geological times, what we had we still have. Water can be polluted and misused but it is neither created nor destroyed, there is no evidence that water vapor escapes into space. Every year the turnover of water on Earth involves 577,000 km3 of water and this is water that evaporates from the oceanic surface and from land. The same amount of falls as atmospheric precipitation,458,000 km3 on the ocean and 119,000 km3 on land.
The difference between precipitation and evaporation from the surface represents the total runoff of the Earths rivers. These are the sources of fresh water to support life necessities
Rhenium is a chemical element with symbol Re and atomic number 75. It is a silvery-white, third-row transition metal in group 7 of the periodic table, with an estimated average concentration of 1 part per billion, rhenium is one of the rarest elements in the Earths crust. Rhenium shows in its compounds a variety of oxidation states ranging from −1 to +7. Discovered in 1925, rhenium was the last stable element to be discovered and it was named after the river Rhine in Europe. Nickel-based superalloys of rhenium are used in the chambers, turbine blades. These alloys contain up to 6% rhenium, making jet engine construction the largest single use for the element, rhenium was the last-discovered of the elements that have a stable isotope. The existence of an element at this position in the periodic table had been first predicted by Dmitri Mendeleev. Other calculated information was obtained by Henry Moseley in 1914 and it is generally considered to have been discovered by Walter Noddack, Ida Tacke, and Otto Berg in Germany.
In 1925 they reported that they had detected the element in platinum ore and they found rhenium in gadolinite and molybdenite. In 1928 they were able to extract 1 g of the element by processing 660 kg of molybdenite and it was estimated in 1968 that 75% of the rhenium metal in the United States was used for research and the development of refractory metal alloys. It took several years from that point before the superalloys became widely used, in 1908, Japanese chemist Masataka Ogawa announced that he had discovered the 43rd element and named it nipponium after Japan. However, recent analysis indicated the presence of rhenium, not element 43, the symbol Np was used for the element neptunium, and the name nihonium, named after Japan, along with symbol Nh, represents element 113. Rhenium is a metal with one of the highest melting points of all elements, exceeded by only tungsten. It has one of the highest boiling point of all elements and it is one of the densest, exceeded only by platinum and osmium.
Rhenium has a hexagonal close-packed crystal structure, with parameters a =276.1 pm. Its usual commercial form is a powder, but this element can be consolidated by pressing and sintering in a vacuum or hydrogen atmosphere and this procedure yields a compact solid having a density above 90% of the density of the metal. When annealed this metal is very ductile and can be bent, rhenium-molybdenum alloys are superconductive at 10 K, tungsten-rhenium alloys are superconductive around 4–8 K, depending on the alloy. Rhenium metal superconducts at 1.697 ±0.006 K, in bulk form and at room temperature and atmospheric pressure, the element resists alkalis, sulfuric acid, hydrochloric acid, dilute nitric acid, and aqua regia