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T. Rex And The Crater Of Doom
''T. rex and the Crater of Doom'' is a nonfiction book by professor Walter Alvarez that was published by Princeton University Press in 1997. The book discusses the research and evidence that led to the creation of the Alvarez hypothesis, which explains how an impact event was the main cause that resulted in the Cretaceous–Paleogene extinction event. Content The book begins by discussing Alvarez's research in the 1970s, before ever investigating the cause of the Cretaceous–Paleogene extinction event, when he was researching plate tectonics involving the Apennine Mountains with William "Bill" Lowrie. The method of this research was to use the evidence of the Earth's magnetic field to show that the plate upon which the rocks of the mountains rested had rotated over millions of years. While investigating limestone deposits in Gubbio, they discovered that some of the rocks were not aligned with the magnetic north pole, but in the opposite direction, implying the Earth undergoes ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Walter Alvarez
Walter Alvarez (born October 3, 1940) is a professor in the Earth and Planetary Science department at the University of California, Berkeley. He is most widely known for the theory that dinosaurs were killed by an asteroid impact, developed in collaboration with his father, Nobel Prize–winning physicist Luis Alvarez. Biography Born in Berkeley, California, Alvarez is the son of Luis Walter Alvarez, a Nobel prize-winner in physics, and Geraldine Smithwick. His grandfather was the famed physician Walter C. Alvarez and his great-grandfather, Spanish-born Luis F. Alvarez, worked as a doctor in Hawaii and developed a method for the better diagnosis of macular leprosy. His great-aunt Mabel Alvarez was a noted California artist and oil painter. Alvarez earned his B.A. in geology in 1962 from Carleton College in Minnesota and Ph.D. in geology from Princeton University in 1967. He worked for American Overseas Petroleum Limited in the Netherlands, and in Libya at the time of Colone ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Geomagnetic Reversal
A geomagnetic reversal is a change in a planet's magnetic field such that the positions of magnetic north and magnetic south are interchanged (not to be confused with geographic north and geographic south). The Earth's field has alternated between periods of ''normal'' polarity, in which the predominant direction of the field was the same as the present direction, and ''reverse'' polarity, in which it was the opposite. These periods are called '' chrons''. Reversal occurrences are statistically random. There have been at least 183 reversals over the last 83 million years (on average once every ~450,000 years). The latest, the Brunhes–Matuyama reversal, occurred 780,000 years ago, with widely varying estimates of how quickly it happened. Other sources estimate that the time that it takes for a reversal to complete is on average around 7,000 years for the four most recent reversals. Clement (2004) suggests that this duration is dependent on latitude, with shorter durations at ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gamma Ray Bursts
In gamma-ray astronomy, gamma-ray bursts (GRBs) are immensely energetic explosions that have been observed in distant galaxies. They are the most energetic and luminous electromagnetic events since the Big Bang. Bursts can last from ten milliseconds to several hours. After an initial flash of gamma rays, a longer-lived "afterglow" is usually emitted at longer wavelengths (X-ray, ultraviolet, optical, infrared, microwave and radio). The intense radiation of most observed GRBs is thought to be released during a supernova or superluminous supernova as a high-mass star implodes to form a neutron star or a black hole. A subclass of GRBs appear to originate from the merger of binary neutron stars. The sources of most GRBs are billions of light years away from Earth, implying that the explosions are both extremely energetic (a typical burst releases as much energy in a few seconds as the Sun will in its entire 10-billion-year lifetime) and extremely rare (a few per galaxy per mil ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Supernova
A supernova is a powerful and luminous explosion of a star. It has the plural form supernovae or supernovas, and is abbreviated SN or SNe. This transient astronomical event occurs during the last evolutionary stages of a massive star or when a white dwarf is triggered into runaway nuclear fusion. The original object, called the ''progenitor'', either collapses to a neutron star or black hole, or is completely destroyed. The peak optical luminosity of a supernova can be comparable to that of an entire galaxy before fading over several weeks or months. Supernovae are more energetic than novae. In Latin, ''nova'' means "new", referring astronomically to what appears to be a temporary new bright star. Adding the prefix "super-" distinguishes supernovae from ordinary novae, which are far less luminous. The word ''supernova'' was coined by Walter Baade and Fritz Zwicky in 1929. The last supernova to be directly observed in the Milky Way was Kepler's Supernova in 1604, appea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Zealand
Zealand ( da, Sjælland ) at 7,031 km2 is the largest and most populous island in Denmark proper (thus excluding Greenland and Disko Island, which are larger in size). Zealand had a population of 2,319,705 on 1 January 2020. It is the 13th-largest island in Europe by area and the 4th most populous. It is connected to Sprogø and Funen by the Great Belt Fixed Link and to Amager by several bridges in Copenhagen. Indirectly, through the island of Amager and the Øresund Bridge, it is also linked to Scania in Sweden. In the south, the Storstrøm Bridge and the Farø Bridges connect it to Falster, and beyond that island to Lolland, from where the Fehmarnbelt Tunnel to Germany is planned. Copenhagen, the capital of Denmark, with a population between 1.3 and 1.4 million people in 2020, is located mostly on the eastern shore of Zealand and partly on the island of Amager. Other cities on Zealand include Roskilde, Hillerød, Næstved, Helsingør, Slagelse, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stevns Klint
Stevns Klint, known as the Cliffs of Stevns in English, is a white chalk cliff located some southeast of Store Heddinge on the Danish island of Zealand. Stretching along the coast, it is of geological importance as one of the best exposed Cretaceous-Tertiary (K/T) boundaries in the world. Subject to frequent erosion, the cliff rises to a height of up to . Because of its exceptional fossil record, Stevens Klint was inscribed on the UNESCO World Heritage List in 2014. Geology The cliff reveals sections from the uppermost part of the Maastrichtian stage (72 to 66 million years ago), known as the Tor Formation and from the lowermost part of the Danian stage (66 to 62 million years ago); the Danian-aged rocks are known as the Rødvig Formation and the Stevns Klint Formation. The lower strata from the cliff are from the Cretaceous and are composed of soft chalk, indicating a relatively deep marine depositional environment. The dark layer of , mainly five to ten centimeters th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Parts Per Billion
In science and engineering, the parts-per notation is a set of pseudo-units to describe small values of miscellaneous dimensionless quantities, e.g. mole fraction or mass fraction. Since these fractions are quantity-per-quantity measures, they are pure numbers with no associated units of measurement. Commonly used are parts-per-million (ppm, ), parts-per-billion (ppb, ), parts-per-trillion (ppt, ) and parts-per-quadrillion (ppq, ). This notation is not part of the International System of Units (SI) system and its meaning is ambiguous. Overview Parts-per notation is often used describing dilute solutions in chemistry, for instance, the relative abundance of dissolved minerals or pollutants in water. The quantity "1 ppm" can be used for a mass fraction if a water-borne pollutant is present at one-millionth of a gram per gram of sample solution. When working with aqueous solutions, it is common to assume that the density of water is 1.00 g/mL. Therefore, it is common to e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cosmic Dust
Cosmic dust, also called extraterrestrial dust, star dust or space dust, is dust which exists in outer space, or has fallen on Earth. Most cosmic dust particles measure between a few molecules and 0.1 mm (100 micrometers). Larger particles are called meteoroids. Cosmic dust can be further distinguished by its astronomical location: intergalactic dust, interstellar dust, interplanetary dust (such as in the zodiacal cloud) and circumplanetary dust (such as in a planetary ring). There are several methods to obtain space dust measurement. In the Solar System, interplanetary dust causes the zodiacal light. Solar System dust includes comet dust, asteroidal dust, dust from the Kuiper belt, and interstellar dust passing through the Solar System. Thousands of tons of cosmic dust are estimated to reach the Earth's surface every year, [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Science & Education
''Science & Education: Contributions from History, Philosophy, and Sociology of Science and Mathematics'' is a peer-reviewed academic journal published by Springer Science+Business Media. It covers the roles and uses of history and philosophy of science and sociology of science in the teaching of science and mathematics. , the editor-in-chief is Sibel Erduran, who succeeded Kostas Kampourakis (University of Geneva), who in turn succeeded founding editor Michael R. Matthews (University of New South Wales). According to the ''Journal Citation Reports'', the journal has a 2017 impact factor The impact factor (IF) or journal impact factor (JIF) of an academic journal is a scientometric index calculated by Clarivate that reflects the yearly mean number of citations of articles published in the last two years in a given journal, as ... of 1.265. References External links * Education journals Philosophy journals English-language journals Springer Science+Business Media a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Catastrophism
In geology, catastrophism theorises that the Earth has largely been shaped by sudden, short-lived, violent events, possibly worldwide in scope. This contrasts with uniformitarianism (sometimes called gradualism), according to which slow incremental changes, such as erosion, brought about all the Earth's geological features. The proponents of uniformitarianism held that the present was "the key to the past", and that all geological processes (such as erosion) throughout the past resembled those that can be observed today. Since the 19th-century disputes between catastrophists and uniformitarians, a more inclusive and integrated view of geologic events has developed, in which the scientific consensus accepts that some catastrophic events occurred in the geologic past, but regards these as explicable as extreme examples of natural processes which can occur. Proponents of catastrophism proposed that each geological epoch ended with violent and sudden natural catastrophes such as majo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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