Tuesday, 8 April 2014

4.4 billion-year-old zircon is the oldest-known fragment of Earth

Scientists using two different age-determining techniques have shown that a tiny zircon crystal found on a sheep ranch in western Australia dates back to 4.4 billion years ago.

"This is the oldest reliably dated piece of the Earth that we have, that anyone knows of," John Valley told CBS News. Valley, a University of Wisconsin geoscience professor, led the research team. Writing in the journal Nature Geoscience on Sunday, the team said the discovery indicates that Earth's crust formed relatively soon after the planet formed and that the little gem was a remnant of it.
To put that age in perspective, the Earth itself formed 4.5 billion years ago as a ball of molten rock, meaning that its crust formed relatively soon thereafter, 100 million years later. The age of the crystal also means that the crust appeared just 160 million years after the very formation of the solar system.
The oldest fossil records of life are stromatolites produced by an archaic form of bacteria from about 3.4 billion years ago. The zircon was extracted in 2001 from a rock outcrop in Australia's Jack Hills region. For a rock of such importance, it is rather small. It measures only about 200 by 400 microns, about twice the diameter of a human hair.


http://www.dailymail.co.uk/sciencetech/article-2566588/Rock-Ages-Microscopic-4-4-billion-year-old-crystal-oldest-known-fragment-Earth.html

See ------> http://pennystockjournal.blogspot.ca/2013/12/zircon.html