Explain about the age of the earth
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It is really an interesting question as so far Earth scientists have not yet found out conclusively the precise age. The major obstacles to determine the precise age of the Earth directly from Earth rocks is that the oldest rocks have been greatly destroyed, altered and modified many times in earth's history due the processes of the plate tectonics. One most plausible way to find out the age to determine the age of the Solar System and to calculate an age for the Earth by the belief that the Earth and the other solid bodies within the Solar System have also formed at the same time and are, therefore, of the same age.
One method to calculate the age is the measurement of of decay of long-lived radioactive isotopes elements. These experiments are being done on the rocks of Earth, Moon and meteorites are measured by the decay of radioactive isotopes of elements that occur naturally in rocks and minerals and that decay with half lives of 700 million to more than 100 billion years to stable isotopes of other elements.
Rocks exceeding 3.5 billion years are found but oldest rock record, Acasta Gneiss is found in northwestern Canada near Great Slave Lake i.e. 4 billion years old and 3.7 to 3.8 billion years Isua Supracrustal rocks in West Greenland but well-studied rocks nearly as old are also found in the Minnesota River Valley and northern Michigan (3.5-3.7 billion years#, in Swaziland #3.4-3.5 billion years#, and in Western Australia #3.4-3.6 billion years). Interestingly, these ancient rocks are not from any sort of "primordial crust" but are lava flows and sediments deposited in shallow water, an indication that Earth history began well before these rocks were deposited.
A single zircon crystal in sedimentary rocks which was found in Western Australia, showed radiometric age of 4.3 billion years which is probably the oldest materials to be found on Earth so far but what is the origin and source of this zircon crystal is not yet known.
Thousands of meteorites, which are fragments of asteroids that fall to Earth, have been recovered. These primitive objects provide the best ages for the time of formation of the Solar System. There are more than 70 meteorites, of different types, whose ages have been measured using radiometric dating techniques conclude that meteorites, and therefore the Solar System, formed between 4.53 and 4.58 billion years ago.
For additional information on this subject, please see the this video which will know more about Earth.
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