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Encyclopedia > Age of the Earth
Earth as seen from Apollo 17

Modern geologists consider the age of the Earth to be around 4.54 billion years (4.54×109 years).[1] This age was determined by combining the interpretations of oldest-known terrestrial minerals – small crystals of zircon from the Jack Hills of Western Australia – and astronomers' and planetologists' determinations of the age of the solar system based in part on radiometric age dating of meteorite material and lunar samples. Image File history File links Metadata Size of this preview: 599 × 599 pixelsFull resolution (3000 × 3002 pixel, file size: 6. ... Image File history File links Metadata Size of this preview: 599 × 599 pixelsFull resolution (3000 × 3002 pixel, file size: 6. ... This article includes a list of works cited but its sources remain unclear because it lacks in-text citations. ... One thousand million (1,000,000,000) is the natural number following 999,999,999 and preceding 1,000,000,001. ... For other uses, see Mineral (disambiguation). ... Zircon is a mineral belonging to the group of nesosilicates. ... Location of the Jack Hills in Australia Jack Hills The Jack Hills are located in the Narryer Gneiss Terrane of the Yilgarn Craton, Western Australia, and comprise an 80 km long northeast-trending belt of folded and metamorphosed supracrustal rocks. ... Slogan or Nickname: Wildflower State or the Golden State Other Australian states and territories Capital Perth Government Constitutional monarchy Governor Ken Michael Premier Alan Carpenter (ALP) Federal representation  - House seats 15  - Senate seats 12 Gross State Product (2005-06)  - Product ($m)  $107,910 (4th)  - Product per capita  $53,134/person... An astronomer or astrophysicist is a person whose area of interest is astronomy or astrophysics. ... Planetary science, also known as planetology or planetary astronomy, is the science of planets, or planetary systems, and the solar system. ... This article is about the Solar System. ... Willamette Meteorite A meteorite is a natural object originating in outer space that survives an impact with the Earths surface without being destroyed. ... Crust composition Oxygen 43% Silicon 21% Aluminium 10% Calcium 9% Iron 9% Magnesium 5% Titanium 2% Nickel 0. ...


Historically the age of the Earth was determined either by using the accounts of creation in religious texts, or by philosophical interpretations of geologic features, most notably the Greek philosophers Theophrastus and Xenophanes. Some Biblical young earth creationists believe that the earth was formed as recently as 4004 BC, whereas Hindu beliefs have the universe enduring for billions of years before being destroyed and recreated in an endless cycle. Bill Reids sculpture The Raven and The First Men, showing part of a Haida creation story. ... Philosophy (from the Greek words philos and sophia meaning love of wisdom) is understood in different ways historically and by different philosophers. ... Geology (from Greek γη- (ge-, the earth) and λογος (logos, word, reason)) is the science and study of the Earth, its composition, structure, physical properties, history, and the processes that shape it. ... A philosopher is a person who thinks deeply regarding people, society, the world, and/or the universe. ... Theophrastus (Greek Θεόφραστος, 370 — about 285 BC), a native of Eressos in Lesbos, was the successor of Aristotle in the Peripatetic school. ... Xenophanes of Colophon (Greek: Ξενοφάνης, 570 BC-480 BC) was a Greek philosopher, poet, and social and religious critic. ... The Bible (From Greek βιβλια—biblia, meaning books, which in turn is derived from βυβλος—byblos meaning papyrus, from the ancient Phoenician city of Byblos which exported papyrus) is the sacred scripture of Christianity. ... Young Earth creationism is the belief that the Earth and life on Earth were created by a direct action of God a relatively short time ago. ... This article discusses the adherents of Hinduism. ... For other uses, see Universe (disambiguation). ...


After the scientific revolution and the discovery of radiometric age dating, measurements of zircons indicate that the Earth is at least 4.404 billion years old. Comparing the mass and luminosity of the Sun to the multitudes of other stars, it appears that the solar system cannot be much older than those rocks. Ca-Al-rich inclusions (inclusions rich in calcium and aluminium) – the oldest known solid constituents within meteorites which are formed within the solar system – are 4.567 billion years old, giving an age for the solar system and an upper limit for the age of the Earth. It is assumed that the accretion of the Earth began soon after the formation of the Ca-Al-rich inclusions and the meteorites. Because the exact accretion time of the Earth is not yet known, and the predictions from different accretion models vary from several millions up to about 100 million years, the exact age of the Earth is difficult to determine. This article is about the period or event in history. ... Radiometric dating (often called radioactive dating) is a technique used to date materials, based on a comparison between the observed abundance of particular naturally occurring radioactive isotopes and their known decay rates. ... Zircon is a mineral belonging to the group of nesosilicates. ... For other uses, see Mass (disambiguation). ... This article does not cite any references or sources. ... Sol redirects here. ... This article is about the astronomical object. ... Ca-Al-rich inclusions (CAIs) are centimeter sized light-coloured inclusions found in carbonaceous chondrites. ... For other uses, see Calcium (disambiguation). ... Aluminum redirects here. ... Worlds second largest Meteorite in Culiacan, Mexico A meteorite is a relatively small extra-terrestrial body that reaches the Earths surface. ...

Contents

Development of modern geologic concepts

Studies of strata, the layering of rock and earth, gave naturalists an appreciation that the Earth may have been through many changes during its existence. These layers often contained fossilized remains of unknown creatures, leading some to interpret a progression of organisms from layer to layer. Xenophanes interpreted fossil-bearing strata in much the same way during the 6th Century BC. For other uses, see strata (novel) and strata title. ... Table of natural history, 1728 Cyclopaedia Natural history is an umbrella term for what are now often viewed as several distinct scientific disciplines of integrative organismal biology. ... For other uses, see Fossil (disambiguation). ... Xenophanes of Colophon (Greek: Ξενοφάνης, 570 BC-480 BC) was a Greek philosopher, poet, and social and religious critic. ...


Nicolas Steno (17th Century) was one of the first Western naturalists to appreciate the connection between fossil remains and strata. His observations led him to formulate important stratigraphic concepts (i.e., the "law of superposition" and the "principle of original horizontality"). In the 1790s, the British naturalist William Smith hypothesized that if two layers of rock at widely differing locations contained similar fossils, then it was very plausible that the layers were the same age. William Smith's nephew and student, John Phillips, later calculated by such means that the Earth was about 96 million years old. Nicolaus Steno. ... Stratigraphy, a branch of geology, studies rock layers and layering (stratification). ... See here for the superposition principle of physics. ... Proposed by Nicholas Steno. ... William Smith. ... For other people with this name, see John Phillips John Phillips (December 25, 1800 – April 24, 1874) was an English geologist. ...


The naturalist Mikhail Lomonosov, regarded as the founder of Russian science, suggested in the mid-18th century that the Earth had been created separately from the rest of the universe, several hundred thousand years before. Lomonosov's ideas were mostly speculative, but in 1779, the French naturalist the Comte du Buffon tried to obtain a value for the age of the Earth using an experiment: He created a small globe that resembled the Earth in composition and then measured its rate of cooling. This led him to estimate that the Earth was about 75,000 years old. For other uses, see Lomonosov (disambiguation). ... Georges-Louis Leclerc, Comte de Buffon, by François-Hubert Drouais (1727-1775). ...


Other naturalists used these hypotheses to construct a history of Earth, though their timelines were inexact as they did not know how long it took to lay down stratigraphic layers. In 1830, the geologist Charles Lyell, developing ideas found in Scottish natural philosopher James Hutton, popularized the concept that the features of the Earth were in perpetual change, eroding and reforming continuously, and the rate of this change was roughly constant. This was a challenge to the traditional view, which saw the history of the Earth as static, with changes brought about by intermittent catastrophes. Many naturalists were influenced by Lyell to become "uniformitarians" who believed that changes were constant and uniform. Geological time put in a diagram called a geological clock, showing the relative lengths of the eons of the Earths history. ... Charles Lyell The frontispiece from Principles of Geology Sir Charles Lyell, 1st Baronet, KT, (November 14, 1797 – February 22, 1875) was a Scottish lawyer, geologist, and populariser of uniformitarianism. ... James Hutton, painted by Abner Lowe. ... Catastrophe (Gk. ...


Early calculations: physicists, geologists and biologists

In 1862, the physicist William Thomson (who later became Lord Kelvin) of Glasgow published calculations that fixed the age of the Earth at between 24 million and 400 million years.[2][3] He assumed that the Earth had been created as a completely molten ball of rock, and determined the amount of time it took for the ball to cool to its present temperature. His calculations did not account for the ongoing heat source in the form of radioactive decay, which was unknown at the time. William Thomson, Archbishop of York, has the same name as this man. ... For other uses, see Glasgow (disambiguation). ...


Geologists had trouble accepting such a short age for the Earth. Biologists could accept that the Earth might have a finite age, but even 100 million years seemed much too short to be plausible. Charles Darwin, who had studied Lyell's work, had proposed his theory of the evolution of organisms by natural selection, a process whose combination of random heritable variation and cumulative selection implies great expanses of time. Even 400 million years did not seem long enough. For other people of the same surname, and places and things named after Charles Darwin, see Darwin. ... This article is about evolution in biology. ... For other uses, see Natural selection (disambiguation). ...


In a lecture in 1869, Darwin's great advocate, Thomas H. Huxley, attacked Thomson's calculations, suggesting they appeared precise in themselves but were based on faulty assumptions. The German physicist Hermann von Helmholtz (in 1856) and the Canadian astronomer Simon Newcomb (in 1892) contributed their own calculations of 22 and 18 million years respectively to the debate: they independently calculated the amount of time it would take for the Sun to condense down to its current diameter and brightness from the nebula of gas and dust from which it was born.[3] Their values were consistent with Thomson's calculations. However, they assumed that the Sun was only glowing from the heat of its gravitational contraction. The process of solar nuclear fusion was not yet known to science. Thomas Henry Huxley, FRS (4 May 1825 – 29 June 1895) [1] was an English biologist, known as Darwins Bulldog for his advocacy of Charles Darwins theory of evolution. ... Hermann Ludwig Ferdinand von Helmholtz (August 31, 1821 – September 8, 1894) was a German physician and physicist. ... Simon Newcomb. ... Star formation is the process by which dense parts of molecular clouds collapse into a ball of plasma to form a star. ... The deuterium-tritium (D-T) fusion reaction is considered the most promising for producing fusion power. ...


Other scientists backed up Thomson's figures as well. Charles Darwin's son, the astronomer George H. Darwin of the University of Cambridge, proposed that the Earth and Moon had broken apart in their early days when they were both molten. He calculated the amount of time it would have taken for tidal friction to give the Earth its current 24-hour day. His value of 56 million years added additional evidence that Thomson was on the right track.[3] For other people of the same surname, and places and things named after Charles Darwin, see Darwin. ... George Howard Darwin (1845-1912) Sir George Howard Darwin, F.R.S. (July 9, 1845 – December 7, 1912) was a British astronomer and mathematician, the second son and fifth child of Charles and Emma Darwin. ... The University of Cambridge (often Cambridge University), located in Cambridge, England, is the second-oldest university in the English-speaking world and has a reputation as one of the worlds most prestigious universities. ... This article is about Earths moon. ... It has been suggested that Tidal friction be merged into this article or section. ...


In 1899 and 1900, John Joly of the University of Dublin calculated the rate at which the oceans should have accumulated salt from erosion processes, and determined that the oceans were about 80 to 100 million years old.[3] John Joly (November 1, 1857 – December 8, 1933) was an Irish scientist, possibly most famous for his development of radiotherapy in the treatment of cancer. ... The University of Dublin, corporately designated the Chancellor, Doctors and Masters of the University of Dublin located in Dublin, Ireland, was founded in 1592 by Queen Elizabeth I, making it Irelands oldest university. ... For Halite Bittorrent client , see Halite Client. ... For morphological image processing operations, see Erosion (morphology). ...


Radioactive dating

Main article: Radiometric dating

Radiometric dating (often called radioactive dating) is a technique used to date materials, based on a comparison between the observed abundance of particular naturally occurring radioactive isotopes and their known decay rates. ...

Overview

Rock minerals naturally contain certain elements and not others. By the process of radioactive decay of radioactive isotopes occurring in a rock, exotic elements can be introduced over time. By measuring the concentration of the stable end product of the decay, coupled with knowledge of the half life and initial concentration of the decaying element, the age of the rock can be calculated. Typical radioactive end products are argon from potassium-40 and lead from uranium and thorium decay. If the rock becomes molten, as happens in the Earth's mantle, such non radioactive end products typically escape or are redistributed. Thus the age of the oldest terrestrial rock gives a minimum for the age of the Earth assuming that a rock cannot have been in existence for longer than the Earth itself. Rock redirects here. ... For other uses, see Mineral (disambiguation). ... The periodic table of the chemical elements A chemical element, or element, is a type of atom that is defined by its atomic number; that is, by the number of protons in its nucleus. ... Radioactive decay is the process in which an unstable atomic nucleus loses energy by emitting radiation in the form of particles or electromagnetic waves. ... For other uses, see Concentration (disambiguation). ... This article is about the computer game. ... General Name, symbol, number argon, Ar, 18 Chemical series noble gases Group, period, block 18, 3, p Appearance colorless Standard atomic weight 39. ... General Name, symbol, number potassium, K, 19 Chemical series alkali metals Group, period, block 1, 4, s Appearance silvery white Standard atomic weight 39. ... This article is about the metal. ... This article is about the chemical element. ... General Name, Symbol, Number thorium, Th, 90 Chemical series Actinides Group, Period, Block n/a, 7, f Appearance silvery white Standard atomic weight 232. ... Earth cutaway from core to exosphere. ...


Convective mantle and radioactivity

In 1892, Thomson had been made Lord Kelvin in appreciation of his many scientific accomplishments. Kelvin calculated the age of the Earth by using thermal gradients, and arrived at an estimate of 100 million years old. [4] He did not realize that Earth has a molten fluid mantle, and this ruined his calculation. In 1895, John Perry produced an age of the Earth estimate of 2 to 3 billions years old using a model of a molten convective mantle and thin crust. [4] Kelvin stuck by his estimate of 100 million years, and later reduced the estimate to about 20 million years. William Thomson, Archbishop of York, has the same name as this man. ... Heat conduction or thermal conduction is the spontaneous transfer of thermal energy through matter, from a region of higher temperature to a region of lower temperature, and hence acts to even out temperature differences. ... Earth cutaway from core to exosphere. ... John Perry John Perry (1850-1920) F.R.S. was an Ulsterman and engineer. ...


Radioactivity would introduce another factor in the calculation. In 1896, the French chemist A. Henri Becquerel discovered radioactivity. In 1898, two other French researchers, Marie and Pierre Curie, discovered the radioactive elements polonium and radium. In 1903 Pierre Curie and his associate Albert Laborde announced that radium produces enough heat to melt its own weight in ice in less than an hour. For the SI unit of radioactivity, see Becquerel. ... Radioactivity may mean: Look up radioactivity in Wiktionary, the free dictionary. ... Maria Skłodowska-Curie. ... Pierre Curie (May 15, 1859 – died April 19, 1906) was a French physicist, a pioneer in crystallography, magnetism, piezoelectricity and radioactivity. ... General Name, Symbol, Number polonium, Po, 84 Chemical series metalloids Group, Period, Block 16, 6, p Appearance silvery Standard atomic weight (209) g·mol−1 Electron configuration [Xe] 4f14 5d10 6s2 6p4 Electrons per shell 2, 8, 18, 32, 18, 6 Physical properties Phase solid Density (near r. ... General Name, Symbol, Number radium, Ra, 88 Chemical series alkaline earth metals Group, Period, Block 2, 7, s Appearance silvery white metallic Standard atomic weight (226) g·mol−1 Electron configuration [Rn] 7s2 Electrons per shell 2, 8, 18, 32, 18, 8, 2 Physical properties Phase solid Density (near r. ...


Geologists quickly realized that the discovery of radioactivity upset the assumptions on which most calculations of the age of the Earth were based. These calculations assumed that the Earth and Sun had been created at some time in the past and had been steadily cooling since that time. Radioactivity provided a process that generated heat. George Darwin and Joly were the first to point this out, also in 1903.


There was the issue of whether the Earth contained enough radioactive material to significantly affect its rate of cooling. In 1901 two German schoolteachers, Julius Elster and Hans F. Geitel, had detected radioactivity in the air and then in the soil. Other investigators found it in rainwater, snow, and groundwater. Robert J. Strutt of Imperial College, London, found traces of radium in many rock samples, and concluded that the Earth contained more than enough radioactive material to keep it warm for a long, long time. Groundwater is water located beneath the ground surface in soil pore spaces and in the fractures of lithologic formations. ...


Strutt's work created controversy in the scientific community. Lord Kelvin spoke for those who still believed in the older estimates, fighting a stubborn rear-guard action in public against the new findings up to his death in 1907, though he admitted in private that his calculations had been shown to be incorrect.[citation needed]


Invention of radiometric dating

Radioactivity, which had overthrown the old calculations, yielded a bonus by providing a basis for new calculations, in the form of radiometric dating.


Ernest Rutherford and Frederick Soddy had continued their work on radioactive materials and concluded that radioactivity was due to a spontaneous transmutation of atomic elements. In radioactive decay, an element breaks down into another, lighter element, releasing alpha, beta, or gamma radiation in the process. They also determined that a particular radioactive element decays into another element at a distinctive rate. This rate is given in terms of a "half-life", or the amount of time it takes half of a mass of that radioactive material to break down into its "decay product". Ernest Rutherford, 1st Baron Rutherford of Nelson OM PC FRS (30 August 1871 - 19 October 1937), widely referred to as Lord Rutherford, was a nuclear physicist who became known as the father of nuclear physics. ... Frederick Soddy in 1922. ... Radioactive decay is the process in which an unstable atomic nucleus loses energy by emitting radiation in the form of particles or electromagnetic waves. ... Half-Life For a quantity subject to exponential decay, the half-life is the time required for the quantity to fall to half of its initial value. ...


Some radioactive materials have short half-lives; some have long half-lives. Uranium, thorium, and radium have long half-lives, and so persist in the Earth's crust, but radioactive elements with short half-lives have generally disappeared. This suggested that it might be possible to measure the age of the Earth by determining the relative proportions of radioactive materials in geological samples. In reality, radioactive elements do not always decay into nonradioactive ("stable") elements directly, instead, decaying into other radioactive elements that have their own half-lives and so on, until they reach a stable element. Such "decay series", such as the uranium-radium and thorium series, were known within a few years of the discovery of radioactivity, and provided a basis for constructing techniques of radiometric dating. This article is about the chemical element. ... General Name, Symbol, Number thorium, Th, 90 Chemical series Actinides Group, Period, Block n/a, 7, f Appearance silvery white Standard atomic weight 232. ... General Name, Symbol, Number radium, Ra, 88 Chemical series alkaline earth metals Group, Period, Block 2, 7, s Appearance silvery white metallic Standard atomic weight (226) g·mol−1 Electron configuration [Rn] 7s2 Electrons per shell 2, 8, 18, 32, 18, 8, 2 Physical properties Phase solid Density (near r. ... In nuclear chemistry, the term stable element has been variously defined by different people at different times. ...


The pioneers of radioactivity were Bertram B. Boltwood, a young chemist just out of Yale, and the energetic Rutherford. Boltwood had conducted studies of radioactive materials as a consultant, and when Rutherford lectured at Yale in 1904, Boltwood was inspired to describe the relationships between elements in various decay series. Late in 1904, Rutherford took the first step toward radiometric dating by suggesting that the alpha particles released by radioactive decay could be trapped in a rocky material as helium atoms. At the time, Rutherford was only guessing at the relationship between alpha particles and helium atoms, but he would prove the connection four years later. Bertram Borden Boltwood (July 27, 1870 - 1927) was an American pioneer of radiochemistry. ... Yale redirects here. ... An alpha particle is deflected by a magnetic field Alpha radiation consists of helium-4 nuclei and is readily stopped by a sheet of paper. ... General Name, symbol, number helium, He, 2 Chemical series noble gases Group, period, block 18, 1, s Appearance colorless Standard atomic weight 4. ...


Soddy and Sir William Ramsay, then at University College in London, had just determined the rate at which radium produces alpha particles, and Rutherford proposed that he could determine the age of a rock sample by measuring its concentration of helium. He dated a rock in his possession to an age of 40 million years by this technique. Rutherford wrote, Categories: People stubs | 1852 births | 1916 deaths | Nobel Prize in Chemistry winners | Discoverer of a chemical element ... University College can refer to several institutions: in Canada University College, University of Toronto University College of the North, The Pas, Manitoba University College of the Cariboo, Kamloops, British Columbia, merged with British Columbia Open University and renamed Thompson Rivers University Kings University College (Edmonton), Alberta in England University...

I came into the room, which was half dark, and presently spotted Lord Kelvin in the audience and realized that I was in trouble at the last part of my speech dealing with the age of the earth, where my views conflicted with his. To my relief, Kelvin fell fast asleep, but as I came to the important point, I saw the old bird sit up, open an eye, and cock a baleful glance at me! Then a sudden inspiration came, and I said, 'Lord Kelvin had limited the age of the earth, provided no new source was discovered. That prophetic utterance refers to what we are now considering tonight, radium!' Behold! the old boy beamed upon me.[5]

Rutherford assumed that the rate of decay of radium as determined by Ramsay and Soddy was accurate, and that helium did not escape from the sample over time. Rutherford's scheme was inaccurate, but it was a useful first step.


Boltwood focused on the end products of decay series. In 1905, he suggested that lead was the final stable product of the decay of radium. It was already known that radium was an intermediate product of the decay of uranium. Rutherford joined in, outlining a decay process in which radium emitted five alpha particles through various intermediate products to end up with lead, and speculated that the radium-lead decay chain could be used to date rock samples. Boltwood did the legwork, and by the end of 1905 had provided dates for 26 separate rock samples, ranging from 92 to 570 million years. He did not publish these results, which was fortunate because they were flawed by measurement errors and poor estimates of the half-life of radium. Boltwood refined his work and finally published the results in 1907. This article is about the metal. ...


Boltwood's paper pointed out that samples taken from comparable layers of strata had similar lead-to-uranium ratios, and that samples from older layers had a higher proportion of lead, except where there was evidence that lead had leached out of the sample. However, his studies were flawed by the fact that the decay series of thorium was not understood, which led to incorrect results for samples that contained both uranium and thorium. However, his calculations were far more accurate than any that had been performed to that time. Refinements in the technique would later give ages for Boltwood's 26 samples of 250 million to 1.3 billion years. Leaching is the process of extracting a substance from a solid by dissolving it in a liquid. ...


Arthur Holmes establishes radiometric dating

Although Boltwood published his paper in a prominent geological journal, the geological community had little interest in radioactivity. Boltwood gave up work on radiometric dating and went on to investigate other decay series. Rutherford remained mildly curious about the issue of the age of the Earth but did little work on it.


Robert Strutt tinkered with Rutherford's helium method until 1910 and then ceased. However, Strutt's student Arthur Holmes became interested in radiometric dating and continued to work on it after everyone else had given up. Holmes focused on lead dating, because he regarded the helium method as unpromising. He performed measurements on rock samples and concluded in 1911 that the oldest (a sample from Ceylon) was about 1.6 billion years old.[6] These calculations were not particularly trustworthy. For example, he assumed that the samples had contained only uranium and no lead when they were formed. Arthur Holmes (January 14, 1890 – September 20, 1965) was a British geologist. ...


More important, in 1913 research was published showing that elements generally exist in multiple variants with different masses, or "isotopes". In the 1930s, isotopes would be shown to have nuclei with differing numbers of the neutral particles known as "neutrons". In that same year, other research was published establishing the rules for radioactive decay, allowing more precise identification of decay series. For other uses, see Isotope (disambiguation). ... Properties In physics, the neutron is a subatomic particle with no net electric charge and a mass of 940 MeV/c² (1. ...


Many geologists felt these new discoveries made radiometric dating so complicated as to be worthless. Holmes felt that they gave him tools to improve his techniques, and he plodded ahead with his research, publishing before and after the First World War. His work was generally ignored until the 1920s, though in 1917 Joseph Barrell, a professor of geology at Yale, redrew geological history as it was understood at the time to conform to Holmes's findings in radiometric dating. Barrell's research determined that the layers of strata had not all been laid down at the same rate, and so current rates of geological change could not be used to provide accurate timelines of the history of the Earth.


Holmes's persistence finally began to pay off in 1921, when the speakers at the yearly meeting of the British Association for the Advancement of Science came to a rough consensus that the Earth was a few billion years old, and that radiometric dating was credible. Holmes published The Age of the Earth, an Introduction to Geological Ideas in 1927 in which he presented a range of 1.6 to 3.0 billion years.[7] No great push to embrace radiometric dating followed, however, and the die-hards in the geological community stubbornly resisted. They had never cared for attempts by physicists to intrude in their domain, and had successfully ignored them so far. The growing weight of evidence finally tilted the balance in 1931, when the National Research Council of the US National Academy of Sciences finally decided to resolve the question of the age of the Earth by appointing a committee to investigate. Holmes, being one of the few people on Earth who was trained in radiometric dating techniques, was a committee member, and in fact wrote most of the final report.[7] The British Association or the British Association for the Advancement of Science or the BA is a learned society with the object of promoting science, directing general attention to scientific matters, and facilitating intercourse between scientific workers. ... The National Research Council (NRC) of the USA is the working arm of the United States National Academy of Sciences and the United States National Academy of Engineering, carrying out most of the studies done in their names. ... President Harding and the National Academy of Sciences at the White House, Washington, DC, April 1921 The National Academy of Sciences (NAS) is a corporation in the United States whose members serve pro bono as advisers to the nation on science, engineering, and medicine. ...


The report concluded that radioactive dating was the only reliable means of pinning down geological time scales. Questions of bias were deflected by the great and exacting detail of the report. It described the methods used, the care with which measurements were made, and their error bars and limitations.


Modern radiometric dating

Radiometric dating continues to be the predominant way scientists date geologic timescales. Techniques for radioactive dating have been tested and fine tuned for the past 50+ years. Forty or so different dating techniques are utilized to date a wide variety of materials, and dates for the same sample using these techniques are in very close agreement on the age of the material.


Possible contamination problems do exist, but they have been studied and dealt with by careful investigation; leading to sample preparation procedures being minimized to limit the chance of contamination. Hundreds to thousands of measurements are done daily with excellent precision and accurate results. Even so, research continues to refine and improve radiometric dating to this day.


Why meteorites were used

Today's accepted age of the Earth of 4.55 billion years was determined by C.C. Patterson using Uranium-Lead dating on fragments of the Canyon Diablo meteorite and published in 1956. Clair Cameron Patterson (1922 - 1995) was a geochemist born in Iowa, United States. ... The Canyon Diablo meteorite impacted at Barringer Crater, Arizona and is known from fragments collected around the crater and nearby Canyon Diablo which lies about 3 to 4 miles west of the crater. ...


The quoted age of the Earth is derived, in part, from the Canyon Diablo meteorite for several important reasons and is built upon a modern understanding of cosmochemistry built up over decades of research.


Most geological samples from the Earth are unable to give a direct date of the formation of the Earth from the solar nebula because the Earth has undergone stratification into the core, mantle, and crust, and this has then undergone a long history of mixing and unmixing of these sample reservoirs by plate tectonics, weathering and hydrothermal circulation. Stratification gooberini went to lousville to dance on a praire and then he went down the hill to hang out with jarry. ... The tectonic plates of the world were mapped in the second half of the 20th century. ... Weathering is the decomposition of rocks, soils and their minerals through direct contact with the Earths atmosphere. ... Hydrothermal circulation in the oceans is the passage of the water through mid-ocean Ridge (MOR) systems. ...


All of these processes may adversely affect isotopic dating mechanisms because the sample cannot always be assumed to have remained as a closed system, by which it is meant that either the parent or daughter nucleide or an intermediate daughter nucleide may have been partially removed from the sample, which will skew the resulting isotopic date. To mitigate this effect it is usual to date several minerals in the same sample, to provide an isochron. Alternately, more than one dating system may be used on a sample to check the date.


Some meteorites are furthermore considered to represent the primitive material from which the accreting solar disk was formed. Some have behaved as closed systems (for some isotopic systems) soon after the solar disk and the planets formed. To date, these assumptions are supported by much scientific observation and repeated isotopic dates, and it is certainly a more robust hypothesis than that which assumes a terrestrial rock has retained its original composition.


Nevertheless, ancient Archaean lead ores of galena have been used to date the formation of the Earth as these represent the earliest formed lead-only minerals on the planet and record the earliest homogeneous lead-lead isotope systems on the planet. These have returned age dates of 4.54 billion years with a precision of as little as 1% margin for error.[8] The Archean is a geologic eon; it is a somewhat antiquated term for the time span between 2500 million years before the present and 3800 million years before the present. ... An ore is a mineral deposit containing a metal or other valuable resource in economically viable concentrations. ... For other uses, see Galena (disambiguation). ...


Why the Canyon Diablo meteorite was used

The Canyon Diablo meteorite was used because it is a very large representative of a particularly rare type of meteorite which contains sulfide minerals (particularly troilite), metallic nickel-iron alloys, plus silicate minerals. Formally, sulfide is the dianion, S2−, which exists in strongly alkaline aqueous solutions formed from H2S or alkali metal salts such as Li2S, Na2S, and K2S. Sulfide is exceptionally basic and, with a pKa > 14, it does not exist in appreciable concentrations even in highly alkaline water. ... Pyrrhotite is an unusual iron sulfide mineral with a variable iron content: Fe(1-x)S (x = 0 to 0. ... For other uses, see Nickel (disambiguation). ... For other uses, see Iron (disambiguation). ...


This is important because the presence of the three mineral phases allows investigation of isotopic dates using samples which provide a great separation in concentrations between parent and daughter nuclides. This is particularly true of uranium and lead. Lead is strongly chalcophile and is found in the sulfide at a much greater concentration than in the silicate, versus uranium. Because of this segregation in the parent and daughter nucleides during the formation of the meteorite, this allowed a much more precise date of the formation of the solar disk and hence the planets than ever before. The Goldschmidt Classification, developed by Victor Goldschmidt, is a geochemical classification which groups the chemical elements according to their preferred host phases into siderophile (iron loving), lithophile (silicate loving), chalcophile (sulphur loving), and atmophile (gas loving). ...


The Canyon Diablo date has been backed up by hundreds of other dates, from both terrestrial samples and other meteorites. The meteorite samples, however, show a spread from 4.53 to 4.58 billion years ago. This is interpreted as the duration of formation of the solar nebula and its collapse into the solar disk to form the Sun and the planets. This 50 million year time span allows for accretion of the planets from the original solar dust and meteorites.


The moon as another extraterrestrial body which has not undergone plate tectonics and which has no atmosphere, provides quite precise age dates from the samples returned from the Apollo missions. Rocks returned from the moon have been dated at a maximum of around 4.4 and 4.5 billion years old. Martian meteorites which have landed upon the Earth, have also been dated to around 4.5 billion years old by lead-lead dating.


Altogether the concordance of age dates of both the earliest terrestrial lead reservoirs and all other reservoirs within the solar system found to date are used to support the hypothesis that the Earth and the rest of the solar system formed at around 4.53 to 4.58 billion years ago.


Helioseismic verification

The radiometric date of meteorites can be verified with studies of the Sun. The Sun can be dated using "helioseismic" methods which strongly agree with the radiometric dates found for the oldest meteorites.[9] A computer generated image showing the pattern of a p-mode solar acoustic oscillation both in the interior and on the surface of the sun. ...


Religious beliefs

Certain Hindu puranic views assert that the universe is created, destroyed, and re-created in an eternally repetitive series of cycles. In Hindu cosmology, a universe endures for about 4,320,000,000 years (one day of Brahma, the creator or kalpa) and is then destroyed by fire or water elements. At this point, Brahma rests for one night, just as long as the day. This process, named pralaya (Cataclysm), repeats for 100 Brahma years (311 trillion human years) that represents Brahma's lifespan. According to these puranic views, we are currently believed to be in the 51st year of the present Brahma and so about 155 trillion years have elapsed since he was born as Brahma. After Brahma's 'death', it is necessary that another 100 Brahma years pass until he is reborn and the whole creation begins anew. This process is repeated again and again, forever. This article discusses the adherents of Hinduism. ... Purana (Sanskrit: , meaning tales of ancient times) is the name of an ancient Indian genre (or a group of related genres) of Hindu or Jain literature (as distinct from oral tradition). ... For other uses, see Universe (disambiguation). ... // an egg broke and out came the planets thanks to gods pet hen The Rig Veda describes the origin of the universe as: Then was not non-existence nor existence: there was no realm of air, no sky beyond it. ... A year is the time between two recurrences of an event related to the orbit of the Earth around the Sun. ... This article does not cite any references or sources. ... A kalpa is a Sanskrit word meaning an aeon, or a long period of time in Hindu and Buddhist cosmology. ... Pralaya , in Hindu theosophy , is a period of time of the cycle of existence of the planets where activity does not occur. ...


Jains, followers of Jainism, believe that the earth has existed forever, that it will exist forever, and that over a period of 6 kalm life will be re-created. The Chinese believed that the Earth was created and destroyed in cycles of over 23 million years. The hand with a wheel on the palm symbolizes the Jain Vow of Ahinsa, meaning non-injury and nonviolence. ... Jain and Jaina redirect here. ... According to Jain beliefs, the universe was never created, nor will it ever cease to exist. ...


Several schools of thought in ancient Greece had conceived of the idea of deep time which stretched far into the past, or far into the future beyond the end of humankind. Aristotle thought the Earth and universe had existed from eternity. Prior to Aristotle, Democritus (founder of the Atomist school of thought) believed that the universe consisted of "atoms" and "void", both of which constituted the whole of the universe. He believed that these elements were eternal, never having beginning nor having an end. Leucippus, a contemporary of Democritus, apparently held similar views. Deep time is the theory that Earth is billions of years old and thus had a long history of development and change. ... For other uses, see Aristotle (disambiguation). ... For other uses, see Universe (disambiguation). ... ‎ Democritus (Greek: ) was a pre-Socratic Greek materialist philosopher (born at Abdera in Thrace ca. ... Atomism is the theory that all the objects in the universe are composed of very small particles that were not created and that will have no end. ... Properties For alternative meanings see atom (disambiguation). ... Look up void in Wiktionary, the free dictionary. ... This article is about the philosopher. ... ‎ Democritus (Greek: ) was a pre-Socratic Greek materialist philosopher (born at Abdera in Thrace ca. ...


In modern times, Christian fundamentalists, as well as many Haredi Jews, advocate Young Earth creationism. Generally, they seek to provide a history of the Earth compatible with their religious texts (primarily the book of Genesis; Hebrew, בראשית). Both camps normally hold that the Earth is 6,000 to 10,000 years old,[10] based on the initial creation account of Genesis 1:1 to 2:4, as well as the genealogies of humanity provided in the Bible thereafter. Fundamentalist Christianity, or Christian fundamentalism, is a movement that arose mainly within British and American Protestantism in the late 19th and early 20th centuries by conservative evangelical Christians, who, in a reaction to modernism, actively affirmed a fundamental set of Christian beliefs: the inerrancy of the Bible, Sola Scriptura, the... Haredi Judaism, also called ultra-Orthodox Judaism, is the most theologically conservative form of Judaism. ... Adam and Eve, the first human beings according to Genesis. ... For other uses, see Genesis (disambiguation). ... The word Hebrew most likely means to cross over, referring to the Semitic people crossing over the Euphrates River. ... Genealogy (from Greek: γενεα, genea, family; and λόγος, logos, knowledge) is the study and tracing of family pedigrees. ... This Gutenberg Bible is displayed by the United States Library. ...


There has been some question as to the time frame within the genealogies in Genesis. Some Christians (notably "Old Earth creationists" such as Hugh Ross) interpret the genealogies as non-linear, and that this may raise questions as to the amount of time allowed between ancestor/descendants. In a book published in 1654, not long before his death, Archbishop James Ussher of Armagh, Ireland, calculated from the Bible (augmented by some astronomy and numerology) that creation began on October 23, 4004 BC. Other interpretations (mostly Orthodox Jewish interpretations) point to the use of exact Hebrew grammatical construction in the genealogies; these would include: Usage of the direct object marker 'eth' with wayyoled, and use of hiphil waw consecutive imperfect with the verb yalad, "beget". Other signposts of the text of Genesis being written as strict historical narrative (i.e., extensive use of colophons and waw consecutives throughout) are used to account for a fairly strict genealogy in Genesis, as is confirmed by such Jewish historians as Josephus.[11] This then allows no more than several thousand years to account for human history. This article or section is in need of attention from an expert on the subject. ... Hugh Ross Hugh N. Ross (born 1945) is a Canadian-born Old Earth Creationist. ... Archbishop James Ussher (1581-1656) James Ussher (sometimes spelled Usher) (4 January 1581–21 March 1656) was Anglican Archbishop of Armagh and Primate of All Ireland between 1625–1656 and a prolific religious scholar who most famously published a chronology which calculated the date of Creation as 4004 BC. // Ussher... WGS-84 (GPS) Coordinates: 54. ... For other uses, see Astronomy (disambiguation). ... Numerology is any of many systems, traditions or beliefs in a mystical or esoteric relationship between numbers and physical objects or living things. ... is the 296th day of the year (297th in leap years) in the Gregorian calendar. ... (6th millennium BC – 5th millennium BC – 4th millennium BC – other millennia) Events 4713 BC – The epoch (origin) of the Julian Period described by Joseph Justus Scaliger occurred on January 1, the astronomical Julian day number zero. ... Orthodox Judaism is one of the three major branches of Judaism. ... Eth (Ð, ð), also spelled edh or eð, is a letter used in Old English (Anglo-Saxon) and present-day Icelandic, and in Faroese language which call the letter edd. ... WAW or Waw can mean: the letter Waw in the Hebrew and other alphabets IATA code for Warsaw Frederic Chopin Airport WAW (Australian television station), a satellite broadcast TV station for Western Australia an alternate transliteration of Wau, Sudan World Association of Wrestling a British professional wrestling promotion World at... Colophon (Greek Κολοφών; see also list of traditional Greek place names) was a titular see of Asia Minor. ... WAW or Waw can mean: the letter Waw in the Hebrew and other alphabets IATA code for Warsaw Frederic Chopin Airport WAW (Australian television station), a satellite broadcast TV station for Western Australia an alternate transliteration of Wau, Sudan World Association of Wrestling a British professional wrestling promotion World at... A fanciful representation of Flavius Josephus, in an engraving in William Whistons translation of his works Josephus (37 – sometime after 100 CE),[1] who became known, in his capacity as a Roman citizen, as Titus Flavius Josephus,[2] was a 1st-century Jewish historian and apologist of priestly and...


Following this, many Christians and Haredi Jews, specifically "Young Earth creationists", interpret ancient geologic events based on a flood geology model (a literal interpretation of the Bible's Great Flood narrative in Genesis) to account for many large scale geologic features and most fossil deposits.[12] The concepts of 18th and early 19th century catastrophism are sometimes associated with this view. For other uses, see Christian (disambiguation). ... Haredi Judaism, also called ultra-Orthodox Judaism, is the most theologically conservative form of Judaism. ... Adam and Eve, the first human beings according to Genesis. ... Geology (from Greek γη- (ge-, the earth) and λογος (logos, word, reason)) is the science and study of the Earth, its composition, structure, physical properties, history, and the processes that shape it. ... Flood geology (also creation geology or diluvial geology) is a prominent subset of beliefs under the umbrella of creationism that assumes the literal truth of a global flood as described in the Genesis account of Noahs Ark. ... Look up deluge in Wiktionary, the free dictionary. ... For other uses, see Fossil (disambiguation). ... Catastrophism is the idea that Earth has been affected by sudden, short-lived, violent events that were sometimes worldwide in scope. ...


See also

The age of the universe, in Big Bang cosmology, refers to the time elapsed between the Big Bang and the present day. ... Geochronology is the science of determining the age of rocks, fossils, and sediments. ... Geological time put in a diagram called a geological clock, showing the relative lengths of the eons of the Earths history. ... Radiometric dating (often called radioactive dating) is a technique used to date materials, based on a comparison between the observed abundance of particular naturally occurring radioactive isotopes and their known decay rates. ... // This is a timeline of geological and relevant astronomical events on Earth before the Cambrian period started. ... Table of natural history, 1728 Cyclopaedia Natural history is an umbrella term for what are now often viewed as several distinct scientific disciplines of integrative organismal biology. ...

References

  1. ^ Age of the Earth. U.S. Geological Survey (1997). Retrieved on 2006-01-10.
  2. ^ England P., Molnar P., Richter P., 2007. John Perry's neglected critique of Kelvin's age for the earth: A missed opportunity in geodynamics. GSA Today v.17 (1), 4-9. doi: 10.1130/GSAT01701A.1
  3. ^ a b c d Dalrymple, G. Brent, 1991, The Age of the Earth, Stanford University Press, pp 14-17, ISBN 0-8047-2331-1
  4. ^ a b England, Philip C.; Molnar, Peter & Richter, Frank M. (2007), "Kelvin, Perry and the Age of the Earth", American Scientist 95 (4): pp. 342-349
  5. ^ (1939) Rutherford: Being the Life and Letters of the Rt. Hon. Lord Rutherford, O.M.. Cambridge: Cambridge University Press. 
  6. ^ Dalrymple, G. Brent, 1991, The Age of the Earth, Stanford University Press, pp 74, ISBN 0-8047-2331-1
  7. ^ a b Dalrymple, G. Brent, 1991, The Age of the Earth, Stanford University Press, pp 77-78, ISBN 0-8047-2331-1
  8. ^ Dalrymple, G. Brent, 1991, The Age of the Earth, Stanford University Press, pp 310-341, ISBN 0-8047-2331-1
  9. ^ Bonanno, A., H. Schlattl and L. Paterno, (2006) The age of the sun and relativistic corrections in the EOS, Astronomy and Astrophysics [1]
  10. ^ Archbishop James Ussher (1654), Annales Veteris et Nove Testamenti
  11. ^ Josephus, Jewish Antiquities Books I–IV, Harvard Press, Cambridge, MA, 1930, p. 73; Loeb Classical Library No. 242.
  12. ^ Whitcomb, J. C. & Morris, H. M. (1961), The Genesis Flood, Phillipsburg, NJ: Presbyterian and Reformed Publishing, ISBN 0875523382
  • Carlson R.W. & Tera F., 1998. Lead-Lead Constraints on the time scale of early planetary differentiation. Origin of Earth and Moon Conference, Lunar and Planetary Society. PDF abstract
  • Powell, James Lawrence, 2001, Mysteries of Terra Firma: the Age and Evolution of the Earth, Simon & Schuster, ISBN 0-684-87282-X
  • Terada, K & Sano Y., 2001. In-situ ion microprobe U-Pb dating of phosphates in H-chondrites. in Proceedings of the 11th Annual W.M. Goldschmidt Conference, Lunar and Planetary Society. PDF abstract
  • Valley, John W., William H. Peck, Elizabeth M. King (1999) Zircons Are Forever, The Outcrop for 1999, University of Wisconsin-Madison Wgeology.wisc.edu – Evidence from detrital zircons for the existence of continental crust and oceans on the Earth 4.4 Gyr ago Accessed Jan. 10, 2006
  • Wilde S.A., Valley J.W., Peck W.H. and Graham C.M. (2001) Evidence from detrital zircons for the existence of continental crust and oceans on the Earth 4.4 Gyr ago. Nature, v. 409, pp. 175-178.
  • Wyche, S., D. R. Nelson and A. Riganti (2004) 4350–3130 Ma detrital zircons in the Southern Cross Granite–Greenstone Terrane, Western Australia: implications for the early evolution of the Yilgarn Craton, Australian Journal of Earth Sciences Volume 51 Zircon ages from W. Australia - Abstract Accessed Jan. 10, 2006

Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... is the 10th day of the year in the Gregorian calendar. ...

External links

  • TalkOrigins.org
  • Vectorsite.net – Initial version of this article was based on a public domain text by Greg Goebel
  • USGS preface on the Age of the Earth
  • NASA exposition on the age of Martian meteorites
  • "Aging the Earth", BBC Radio 4 In Our Time series, 2003

Further reading

  • Baadsgaard, H.; Lerbekmo, J.F.; Wijbrans, J.R., 1993. Multimethod radiometric age for a bentonite near the top of the Baculites reesidei Zone of southwestern Saskatchewan (Campanian-Maastrichtian stage boundary?). Canadian Journal of Earth Sciences, v.30, p.769-775.
  • Baadsgaard, H. and Lerbekmo, J.F., 1988. A radiometric age for the Cretaceous-Tertiary boundary based on K-Ar, Rb-Sr, and U-Pb ages of bentonites from Alberta, Saskatchewan, and Montana. Canadian Journal of Earth Sciences, v.25, p.1088-1097.
  • Eberth, D.A. and Braman, D., 1990. Stratigraphy, sedimentology, and vertebrate paleontology of the Judith River Formation (Campanian) near Muddy Lake, west-central Saskatchewan. Bulletin of Canadian Petroleum Geology, v.38, no.4, p.387-406.
  • Goodwin, M.B. and Deino, A.L., 1989. The first radiometric ages from the Judith River Formation (Upper Cretaceous), Hill County, Montana. Canadian Journal of Earth Sciences, v.26, p.1384-1391.
  • Gradstein, F. M.; Agterberg, F.P.; Ogg, J.G.; Hardenbol, J.; van Veen, P.; Thierry, J. and Zehui Huang., 1995. A Triassic, Jurassic and Cretaceous time scale. IN: Bergren, W. A. ; Kent, D.V.; Aubry, M-P. and Hardenbol, J. (eds.), Geochronology, Time Scales, and Global Stratigraphic Correlation. Society of Economic Paleontologists and Mineralogists, Special Publication No. 54, p.95-126.
  • Harland, W.B., Cox, A.V.; Llewellyn, P.G.; Pickton, C.A.G.; Smith, A.G.; and Walters, R., 1982. A Geologic Time Scale: 1982 edition. Cambridge University Press: Cambridge, 131p.
  • Harland, W.B.; Armstrong, R.L.; Cox, A.V.; Craig, L.E.; Smith, A.G.; Smith, D.G., 1990. A Geologic Time Scale, 1989 edition. Cambridge University Press: Cambridge, p.1-263. ISBN 0-521-38765-5
  • Harper, C.W., Jr., 1980. Relative age inference in paleontology. Lethaia, v.13, p.239-248.
  • Lubenow, M.L., 1992. Bones of Contention: A Creationist Assessment of Human Fossils. Baker Book House: Grand Rapids.
  • Obradovich, J.D., 1993. A Cretaceous time scale. IN: Caldwell, W.G.E. and Kauffman, E.G. (eds.). Evolution of the Western Interior Basin. Geological Association of Canada, Special Paper 39, p.379-396.
  • Palmer, Allison R. (compiler), 1983. The Decade of North American Geology 1983 Geologic Time Scale. Geology, v.11, p.503-504. September 12, 2004.

Richard Lee “Dick” Armstrong PhD, FRSC (August 4, 1937 – August 9, 1991) was an American/Canadian scientist who was an expert in the fields of radiogenic isotope geochemistry and geochronology, geochemical evolution of the earth, geology of the American Cordillera, and large-magnitude crustal extension. ... is the 255th day of the year (256th in leap years) in the Gregorian calendar. ... Year 2004 (MMIV) was a leap year starting on Thursday of the Gregorian calendar. ... This article is about Earth as a planet. ... Landscape art depicts scenery such as mountains, valleys, trees, rivers, and forests. ... Central New York City. ... For the history of Earth which includes the time before human existence, see History of Earth. ... This article or section is in need of attention from an expert on the subject. ... In general English usage, the name Earth can be capitalized or spelled in lowercase interchangeably, either when used absolutely or prefixed with the (i. ... This list of countries, arranged alphabetically, gives an overview of countries of the world. ... The world economy can be evaluated in various ways, depending on the model used, and this valuation can then be represented in various ways (for example, in 2006 US dollars). ... For the journal, see Ecology (journal). ... Earth Day Flag. ... A conceptual outline for the program The Millennium Ecosystem Assessment (MA) is a research program that focuses on ecosystem changes over the course of decades, and projecting those changes into the future. ... For other uses, see Fiction (disambiguation). ... A Hollow Earth theory posits that the planet Earth has a hollow interior and, possibly, a habitable inner surface. ... For other uses, see Journey to the Center of the Earth (disambiguation). ... Earth Although nearly all fictional work is set on or features the Earth, this article addresses the depiction in fiction of its existence and role in the universe. ... This article includes a list of works cited but its sources remain unclear because it lacks in-text citations. ... Dymaxion map by Buckminster Fuller shows land mass with minimal distortion as only one continuous continent A continent (Latin continere, to hold together) is a large continuous mass of land on the planet Earth. ... The inner planets. ... A time zone is a region of the Earth that has adopted the same standard time, usually referred to as the local time. ... The goals of the Degree Confluence Project are to visit each of the latitude and longitude integer degree intersections on Earth, and post photographs of each location on the World Wide Web. ... This article is about the natural seismic phenomenon. ... This article describes extreme locations on Earth. ... The tectonic plates of the world were mapped in the second half of the 20th century. ... An equatorial bulge is a planetological term which describes a bulge which a planet may have around its equator, distorting it into an oblate spheroid. ... Earth cutaway from core to exosphere. ... // For other uses, see time scale. ... Geological time put in a diagram called a geological clock, showing the relative lengths of the eons of the Earths history. ... For the history of Earth which includes the time before human existence, see History of Earth. ... This article is about the Solar System. ... Life on Earth  â€¢  â€¢  | Axis scale: millions of years ago. ... Geological time scale. ... The evolutionary history of life and the origin of life are fields of ongoing geological and biological research. ... Google Earth is a virtual globe program that was originally called Earth Viewer and was created by Keyhole, Inc. ... Google Maps (for a time named Google Local) is a free web mapping service application and technology provided by Google that powers many map-based services including the Google Maps website, Google Ride Finder and embedded maps on third-party websites via the Google Maps API. It offers street maps... MSN Virtual Earth in Internet Explorer 6 Live Search Maps (previously Windows Live Maps and Windows Live Local), is a web mapping service provided as a part of Microsofts Windows Live online applications services suite and powered by Microsofts Virtual Earth. // Detailed street maps are available for many... Yahoo! Maps web site Yahoo! Maps is a free online mapping portal provided by the Yahoo! network, based out of Sunnyvale, California. ... Screenshot of World Wind showing USGS Urban Ortho-Imagery of Huntington Beach, Los Angeles World Wind is a virtual globe developed by NASA for use on personal computers running Microsoft Windows. ... Creationism is a religious belief that humanity, life, the Earth, and the universe were created in their original form by a deity or deities (often the Abrahamic God of Judaism, Christianity and Islam), whose existence is presupposed. ... Bill Reids sculpture The Raven and The First Men, showing part of a Haida creation story. ...


  Results from FactBites:
 
Age of the Earth - Wikipedia, the free encyclopedia (4438 words)
This age represents a compromise between the oldest-known terrestrial minerals – small crystals of zircon from the Jack Hills of Western Australia – and astronomers' and planetologists' determinations of the age of the solar system based in part on radiometric age dating of meteorite material and lunar samples.
Today's accepted age of the Earth of 4.55 billion years was determined by C.C. Patterson using Uranium-Lead dating on fragments of the Canyon Diablo meteorite and published in 1956.
USGS preface on the Age of the Earth
Age Of The Earth (524 words)
Scientists generally agree that the answer to the riddle of the age of the earth is carefully concealed within the earth's crust.
Scientists assume the age of an index fossil by the stage of evolutionary history the fossil is assumed to be in.
The popular age of 4.6 billion years old for the planet earth was derived by applying radiometric dating techniques to a meteorite called "allende" (a-yen-day), which scientists assume formed at the same time as the earth.
  More results at FactBites »

 
 

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