[meteorite-list] Uvlade Texas Crater Contorversy

[E. L. Jones]

To save the list from the inane registration process at MySanantonio.com 
site here is the article:
*
Will 'Rosetta Stone' prove Uvalde crater? *

* Web Posted: 01/16/2005 12:00 AM CST *

* Zeke MacCormack
San Antonio Express-News *

UVALDE — The origin of a 2-mile-wide depression outside this town has 
been debated for decades, but a local scientist now claims to have solid 
evidence that it's a meteorite crater.

Bobby Graham rests his case on a rock, measuring roughly 3 feet by 2 
feet, he found in October off U.S. 83 about 15 miles south of the city.

He's convinced that the object he calls "the Uvalde Crater Rosetta 
Stone" was part of the ground where a 300-foot wide meteorite crashed to 
Earth some 30 million years ago.

"I've got the goods," said Graham, 74, who took on the mystery after 
retiring from Sandia National Laboratories, a federal nuclear weapons 
facility, in 1996.

But other scientists are awaiting the results of further investigations 
of the rock, including core sampling and microscopic inspections, before 
reaching any conclusions.

Graham said swirls on the top of the 150-pound caramel-colored rock 
suggest it was once molten. Its middle features small "teardrops" of 
stone, some tinged in red, and the bottom is normal native sandstone.

Its varied features reflect the changes the rock underwent in a split 
second upon impact, "when all the extreme temperature and pressure was 
involved," said Graham, whose specialty during his 38-year career at 
Sandia was the effects of high-pressure shock compression.

He'll present his findings in March at the Lunar and Planetary Science 
Conference in Houston.

"It's not just fascinating; it's important, scientifically, to the world 
to understand these craters," Graham said. "We're sending spacecraft to 
look at craters all over the solar system, but we can learn things here, 
too."

He predicts scientists and tourists alike will flock to see the unusual 
rock, which will anchor a display at the city's new library on what may 
prove to be the fourth known meteorite crater in Texas.

Joining him in addressing the Houston conference will be William 
Feathergail "Feather" Wilson, a geologist who, with son Douglas, is 
credited with identifying the purported crater in 1979 while on a field 
trip with Trinity University students.

"In this area, the rocks are deformed in an extreme fashion, stuff is 
upside down, it's blown out and there's a lot of folding," said Wilson, 
a Bandera County resident.

He says Graham's analysis of the Rosetta Stone bolsters the theory — on 
which the scientific community has waffled — that a meteorite created 
the 1,500-foot depression, which has since been filled in.

"I've always believed it (was a meteorite crater) because we couldn't 
come up with any other conclusion," said Wilson, who first reported his 
findings in Geology magazine in 1979.

The site was included but later removed from the "Earth Impact Data 
Base" maintained by the Planetary and Space Science Center at the 
University of New Brunswick, Canada.

It was delisted because deformed quartz found there — which supported 
the meteorite strike theory — was later found far away, Wilson said.

If proven to be a crater, Wilson said, "it's important from the 
standpoint that out of the 130 to 150 craters on Earth, almost all of 
those have been found in hard rocks. Very few have been found in soft 
water-saturated sedimentary rocks" like those around Uvalde.

Fred Horz, who's familiar with craters from running a NASA experimental 
impact lab, is convinced that a meteorite hit caused the crater, but he 
said Wilson's extensive investigation — which included use of seismic 
mapping — was more convincing than Graham's rock.

"All of the rock strata all over southern Texas are basically 
flat-laying deposits," he said. "In this area, for some reason, they are 
severely fragmented and broken up and even demonstrably transported."

After traveling to see the rock last month, Horz didn't shy from sharing 
some good-natured differences of opinion with Graham.

"It's just a question of interpretation. He sees impact melts and I 
don't," Horz said. "I don't see shocked rocks."