Ancient crystals to be lecture subject

Zircon crystals, the oldest know terrestrial materials, are giving science a new window to the early Earth. A recent study of a zircon dated at 4.4 billion years old by UW–Madison geochemist John Valley revealed evidence that the young planet was far cooler than previously believed and that oceans and continents were emerging at a time when, according to conventional wisdom, the Earth was simply a ball of magma.

Valley will discuss the background of the study and its implications for altering our picture of a nascent Earth in a talk entitled “Zircons are Forever: Evidence for Liquid Water on Earth 4.4 Billion Years Ago” on Friday, Feb. 23 at 3:30 p.m. in Room AB20 Weeks Hall, 1215 W. Dayton St.