Kenneth CHANG,
If the Meteors Didn't Get Dinosaurs, the Lava Did.

[The New York Times, march 23 and 24, 2003].

Scientists are arguing again over the idea that the combination of cataclysms 
that doomed the dinosaurs 65 million years ago - titanic volcanic 
eruptions in India and a meteor impact off the coast of Mexico - may not 
have been a coincidence after all.

For decades, some geologists have theorized that the. force of an extraterrestrial 
rock crashing into Earth could have cracked its crust thousands of 
miles away and allowed molten lava to spill out from the interior. 

But no one has yet found any solid evidence.

Now, though, researchers at University College London are suggesting that 
the Indian lava flows are the impact site of an earlier, larger meteor, and that 
evidence of the impact was upwelling submerged by lava. 

In this view, the mass extinction of dinosaurs and other creatures was caused not 
by a single meteor, but by a barrage of them.

The new work is provoking another burst of theories and debate over the 
demise of the dinosaurs, which has never been explained to everyone's agreement.

The new theory holds that a meteor at least 12 miles wide - at least twice 
as wide as the one that struck Mexico - would melt some rock, but not nearly 
the amount seen in the lava flows, known as the Deccan Traps, which
cover hundreds of thousands of square miles of what is now India. 

Rather, the researchers said, the impact would cause "decompression melting" of 
already hot rocks deep within the Earth.

Computer simulations indicate that once the meteor impact blew away 
overlying rocks, the ones below, relieved of pressure, could then have turned to lava.

"The whole story is what happens underneath the crater," said Dr- Adrian P. Jones, 
a geologist at University College London and lead author of an 
article in the scientific journal Earth and Planetary Science Letters last year.

Dr- Dallas H- Abbott of Columbia University's Lamont-Doherty Earth 
Observatory and Dr- Ann E- Isley of the State University of New York at 
Oswego, writing in the journal, report that their statistical analysis shows, 
with 97 percent confidence, that 9 of 10 periods of heavy meteor bombardment 
corresponded to periods of massive volcanism.

Skeptics like Dr- H- Jay Melosh, a professor of planetary sciences at the 
University of Arizona, are utterly unconvinced.

"It makes a good discussion after beer," he said. "But if you start looking at the details 
and the real evidence for this, it really falls apart".

It may turn out that the dinosaurs were merely very unlucky.