Geologist Wins Top Science Award (Walter Alvarez)

Reno, Nevada (AHN) - Geologist Walter Alvarez will receive the Desert Research Institute's silver medallion and a $20,000 prize.

The Associated Press reports the University of California-Berkeley scientist came up with the theory that dinosaurs were killed off when a comet or asteroid crashed into the Earth.

President of the institute Stephen G. Wells says, "Until the impact theory was finally proven, Dr. Alvarez and his colleagues were regarded as heretics by the `old guard' in the field of geology."

In the 1970s, Alvarez and his team found high levels of Iridium in Italy. The element is exceedingly rare on Earth, but is common in asteroids and comets.

They proposed a theory that said a giant asteroid crashed into the Earth and spewed smoke, dust and iridium into the sky. This blocked the sun and lowered the Earth's temperature, which killed plants and animals.

Few scientists supported his theory when it was published in the journal Science in 1980.

However, evidence of an enormous impact crater found in Mexico's Yucatan Peninsula in 1989 changed some minds.

Ancient Impact Turned Part of Earth Inside-Out
by Robert Roy Britt
4 June 2004
A space rock the size of a large mountain hit 1.8 billion years ago and dredged up part of Earth's lower crust... The evidence comes from a crater in Sudbury, Ontario. Most of the crater was long ago folded into the planet or eroded away. But a section is exposed, revealing minerals and other features that can be compared to more recent craters that are more intact. From all this, scientists gleaned clues to the catastrophic impact. It appears an asteroid about 6 miles (10 kilometers) wide hit the planet at more than 89,000 mph (40 kilometers per second)... Mungall explained that in the top layers of the Sudbury structure, his team found relatively high concentrations of iron, nickel and platinum, stuff that is more common in the lower crust of the planet than in the upper crust (the elements exist in just trace amounts in both regions)... The top layers were also relatively depleted of zirconium, uranium and other elements that tend to show up in other impact sites that only involved melting of the upper crust... Mungall's team also found an enrichment of iridium in the overlying layer at the Sudbury complex, which was already thought to be part of an impact crater.

and BTW, thanks Blam!

Physics News Update Number 16 (Story #2)
by Phillip F. Schewe and Ben Stein
January 10, 1991
The far side of the Moon, impossible to see from the Earth, was recently photographed by the Galileo spacecraft on its way toward Jupiter. New information about the mineralogical composition of the far side's crust was recorded and pictures revealed the largest impact basin yet seen on the moon, more than 2000 km in diameter and so deep that is may have penetrated through the crust to the moon's mantle. (Eos, January 1, 1991.)


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Thanks blam. Note: this topic is dated 3/14/2006. Just adding to the catalog, not sending a general distribution. To all -- please ping me to other topics which are appropriate for the GGG list.

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