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Age of the Earth
Today's accepted age of the earth of 4.55 billion years was first mentioned in 1953 by the geochemist C.C. Patterson at the conference Nuclear Processes in Geologic Settings. This age was based on uranium-lead isotope measurements of the meteorite Canyon Diablo. The time of formation of asteroids - which are the parent bodies of most meteorites - is assumed to be the time when earth formed. Patterson et al. published this determined age in 1955/56 in reviewed journals. The physicist F. Houtermans had already published an age of 4.5 billion years in 1953 in a reviewed journal, but this age was also based on calculations from the same uranium-lead data on Canyon Diablo which were measured by Patterson and therefore not independent from the age determined by Patterson himself. Since then many other isotope systems (Potassium-Argon, Rubidium-Strontium, Samarium-Neodymium) have been used to determine the age of the earth (and of the solar system) and the results confirmed the uranium-lead ages of Patterson and Houtermans.
The oldest minerals which are found on earth are zircons in Australia and show an uranium-lead age of up to about 4.4 billion years. The oldest known minerals which formed in our solar system are CAIs (calcium aluminium-rich inclusions) which can be found within primitive meteorites. The uranium-lead ages of this CAIs were determined to 4.5672 billion years.
Young Earth Creationists disagree with the mainstream age; according to them, the Earth is no older than perhaps a dozen millenia, if that much. The dates such creationists use are generally derived from Archbishop Ussher's centuries-old calculation of the Creation date, at 4004 BC. YEC organizations generally put the lower limit of the age of the earth at 6,000 years, and the higher limit at 12,000 years.
This view, combined with many creationists' insistence that their creationism is scientific, causes them to have serious problems in many fields of science, such as geology, physics, chemistry, archaeology, history and linguistics. For example, YEC's must deal with a variety of geologic structures such as angular unconformities and basalt layering with interbedded paleosols that speak of long periods of time. These structures are important in the old earth/young earth debate as they are readily accessible and can be observed first hand.
- The definition of "Billion" used on EvoWiki is that used commonly in the United States, meaning 1,000,000,000 (one thousand million). Literature written in international English may refer to the age of the earth as 4,550 million years.
- Patterson C., Tilton G. and Inghram M. (1955) "Age of the Earth" Science 212, 69-75.
- Patterson C. (1956) "Age of meteorites and the Earth" Geochimica et Cosmochimica Acta 10, 230-237
- Houtermans, F. (1953) "Determination of the Age of the Earth from the Isotopic Composition of Meteoritic Lead" Nuovo Cimento 10, 1623-1633,
- Wilde S.A.,Valley J.W., Peck W.H., Graham C.M. (2001) "Evidence from detrital zircons for the existence of continental crust and oceans on the Earth 4.4Gyr ago" Nature 409, 175-178