Geologist who linked cosmic strike to dinosaurs' extinction takes...( Walter Alvarez the maverick geo...)

Walter Alvarez, the maverick geologist who convinced a skeptical world that dinosaurs and many other living things on Earth were wiped out by a huge fireball from space, has won the highly esteemed Vetlesen Prize. Considered by many the earth sciences' equivalent of a Nobel, the $250,000 award is funded by the New York-based G. Unger Vetlesen Foundation and administered by Lamont-Doherty Earth Observatory, a member of Columbia University's Earth Institute.

Alvarez was not the first to propose that sudden disasters had drastically altered past life on earth, but the idea ran against conventional wisdom. Since the 1800s, geologists and biologists had seen earth's history mainly in terms of gradual processes, and a stock explanation for dinosaurs' extinction was slowly changing climate. In the mid-1970s, Alvarez was a young field geologist at the University of California, Berkeley, when he was working on an outcrop of limestone near the Italian town of Gubbio. In it, he found a thin layer of red clay in which the shells of tiny sea creatures that previously had existed for eons suddenly disappeared. The seemingly instant extinction dated to 65 million yearsaround the time dinosaurs died out. Together with his father--the Nobel-winning physicist Luis Alvarez--and Berkeley chemists Frank Asaro and Helen Michel, Alvarez discovered that this layer harbored an abnormal amount of iridium, a metal rare in earth's crust but typical of comets and asteroids. In 1980, the scientists proposed that most species of life, including all the dinosaurs, were extinguished when a giant comet or meteorite struck, sending out fireballs and tsunamis, then cooling and darkening the skies with a years-long pall of debris. Among the survivors who later thrived: mammals.

For a decade, Alvarez met with skepticism and even scorn, given lack of a known crater of the right size and age. However, he persisted. Eventually he and others found the iridium layer in
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