MADISON, Wis., June 17 (UPI) — U.S. scientists studying minerals called zircons say a harsh climate might have scoured or even destroyed the surface of the Earth’s earliest continents.
University of Wisconsin-Madison geologist Professor John Valley said Zircons, the oldest known materials on Earth, offer a window in time back as far as 4.4 billion years ago. Because the crystals are exceptionally resistant to chemical changes, Valley said they are now used to determine the age of ancient rocks.