Age of the Earth
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The age of Earth is estimated to be about 4.54 billion years. This value is based on radiometric dating of meteorites, lunar samples, and the oldest minerals and rocks found on Earth.
Because Earth's earliest crust has been repeatedly melted, deformed, and recycled by plate tectonics, very few rocks survive from the planet's first several hundred million years. Zircon crystals in ancient sedimentary rocks preserve some of the oldest dated terrestrial material.
Radiometric dating compares the proportions of radioactive parent isotopes and their decay products. Systems such as uranium–lead dating provide numerical ages because radioactive decay occurs at known rates.
The age estimate is consistent with models of Solar System formation and the dating of primitive meteorites. It establishes the timescale for the formation of Earth's core, crust, oceans, atmosphere, continents, and biological evolution.
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- Source / publisher: Wikipedia
- URL type: WWW
- Credits: Wikipedia
- URL: https://en.wikipedia.org/wiki/Age_of_the_Earth