Oldest dated rocks

The oldest dated rocks on Earth are of several different types.

1. There are early rocks recovered from the Moon. This is relevant because the Moon was once part of the Earth: see giant impact hypothesis. During Apollo 16, Lunar sample 67215, dated at 4.46 billion years, was brought back.Norman M.D. et al 2003. Chronology, geochemistry, and petrology of a ferroan noritic anorthosite clast from Descartes breccia 67215: Clues to the age, origin, structure, and impact history of the lunar crust. Meteoritics and Planetary Science 38, pp. 645–61. Summary Lunar sample 67215 is the oldest known rock on Earth, even though it came from the Moon.

2. The oldest material of terrestrial origin that has been dated is a zircon mineral 4.404 ±0.008 billion years old. It was in the Jack Hills  of Western Australia.Wilde, Simon A. et al 2001. Evidence from detrital zircons for the existence of continental crust and oceans on the Earth 4.4 Gyr ago. Nature Geoscience  The  oldest consistently-dated zircon is closer to 4.35 billion years ago.Wilde S.A. et al 2001. Evidence from detrital zircons for the existence of continental crust and oceans on the Earth 4.4 Gyr ago. Nature 409, pp. 175–78. http://www.geology.wisc.edu/%7Evalley/zircons/Wilde2001Nature.pdf 

3. The oldest rock formation on Earth may be the Acasta Gneiss in the Canadian Shield in the Northwest Territories, Canada. It is composed of the Archaean igneous and gneissic cores of ancient mountain chains that have been exposed by glacial action. Again it was dated by analysis of zircons in the rocks.

 References 

Category:Rocks
Category:Earth
Category:Dating methods