|
Sponsored Links
Modern geologists consider the age of the Earth to be around 4.54 billion years (4.54×109 years).[1] This age has been determined by radiometric age dating of meteorite material[2] and is consistent with the ages of the oldest-known terrestrial and lunar samples. Historically, estimates of the age were based on either creation myths in religious texts, or philosophical interpretations of geologic features, most notably by the Greek philosophers Theophrastus and Xenophanes. 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. Following the scientific revolution and the development of radiometric age dating, measurements of lead in uranium-rich minerals showed that some were in excess of a billion years old.[3] The oldest such minerals analysed to date – small crystals of zircon from the Jack Hills of Western Australia – are at least 4.404 billion years old.[4] 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 that are formed within the solar system – are 4.567 billion years old [5], giving an age for the solar system and an upper limit for the age of the Earth. It is hypothesised 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 range from a few millions up to about 100 million years, the exact age of the Earth is difficult to determine. It is also difficult to determine the exact age of the oldest rocks on Earth, exposed at the surface, as they are aggregates of minerals of possibly different ages. The Acasta Gneiss of Northern Canada may be the oldest known exposed crustal rock. 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.
|
Age Of The Earth Subcategories
Age Of The Earth Articles
|
| 
