posted                   

quote:

---

To create buzz about an otherwise arcane subject, the University of Wisconsin-Madison showed off a tiny speck of zircon crystal believed to be the oldest known piece of Earth at about 4.4 billion years old

Though scientists acknowledged there wasn't much to see, spectators used a microscope to check out the tiny grain, which measures less than two human hairs in diameter.

Analysis of the object in 2001 by John Valley, a UW-Madison professor of geology and geophysics, startled researchers around the world by concluding that the early Earth, instead of being a roiling ocean of magma, was cool enough to have oceans and continents — key conditions for life.

Before its discovery, the oldest evidence for liquid water on the planet was from a rock estimated to be much younger — 3.8 billion years old.

---

quote:

---

The oldest minerals found so far are zircons from the Narryer Gneiss Terrane, Yilgarn Craton, Western Australia, with an age of 4.404 billion years. This age is interpreted to be the age of crystallization. These zircons are not only the oldest minerals on earth, they also show another interesting feature. Their oxygen isotopic composition is interpreted by some to indicate that more than 4.4 billion years ago there was already water on the surface of the earth. This is a spectacular interpretation that has been published in top scientific journals but is widely disputed. It is most likely that the oxygen isotopes, and other compositional features (the rare-earth elements), simply record hydrothermal alteration. The timing of the alteration is uncertain, but this negates the necessity for ancient liquid-water oceans.

---

I dont really have anything to add, I just thought it was interesting

Posts: 2756 | Registered: Jul 2002  |  IP: Logged | 

posted                   

quote:

---

from the Narryer Gneiss Terrane, Yilgarn Craton, Western Australia,

---

Posts: 2756 | Registered: Jul 2002  |  IP: Logged |