[meteorite-list] Sonoma Group Tries To Prove Tektite Find

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Thu Apr 22 10:22:33 2004
Message-ID: <200306021554.IAA26833_at_zagami.jpl.nasa.gov>

http://www.sfgate.com/cgi-bin/article.cgi?f=/c/a/2003/05/30/NB307086.DTL

Sonoma group tries to prove that meteor hit

Cicero A. Estrella,
San Francisco Chronicle
May 30, 2003

Rolfe Erickson carries the black, pebble-sized object everywhere. At any
time, he will pull it out of his pocket and reel off what he believes to be its
2.7 million-year history. No one is safe from his theories.

"I was at my niece's wedding in Seattle," he said. "I showed everybody, and
they could not have been less impressed."

Not yet, but if Erickson is correct, lecture halls will be filling up with
people who want to hear the findings of the Sonoma State University
geology professor. Erickson is out to prove that the "obsidian body of
unknown origin" and 150 others like it collected from Northern California
are evidence of a meteor that might have crashed millions of years ago into
what is now western North America, or at least the water near it.

Erickson suspects the objects are tektites, tiny glass bodies believed to have
formed from young meteorite impacts (35 million years and earlier).
Tektites are found in only five "strewn fields" around the world, including
three that have been linked to meteorite impact sites. Strewn fields cover
up to 1,000 miles. None are known to exist in the western United States.

"If these are indeed tektites, this would be the sixth (strewn field),"
Erickson said.

Erickson became aware of the objects 12 years ago. A woman from
Healdsburg donated a box of 100 to him.

As part of her rehabilitation from surgery, the woman walked the lanes of
a Dry Creek Valley vineyard. She became fascinated by the
charcoal-colored objects and plucked them from the cut soil. She thought
them to be curious- looking pebbles, but a friend suggested they might be
something else and that she bring them to the attention of the university.

Erickson identified them as tektites and sought confirmation from experts.
Radioactive dating by a Canadian laboratory determined they formed during
the upper Pliocene Epoch 2.7 million years ago, but other analyses were not
as telling. Erickson says Arizona State University's Center for Meteorite
Research agreed with his assessment, but the U.S. Geological Survey in
Menlo Park thought they were nothing more than volcanic rock.

The inconclusive analysis brought the project to a halt. Erickson pursued
more pressing projects and stored the box in the bottom drawer of his desk.

His interest was rekindled six months ago, when a student told him of a
similar collection by her uncle, Paul Bernier, a sharecropper for another
Dry Creek Valley vineyard. Erickson began walking local vineyards, paid
closer attention to roadside shoulders and searched other gravelly areas
where the earth has been turned.

"You might see me stopped at a highway, looking at road cuts," Erickson
said.

A third collection surfaced during one of his vineyard visits. Mardy
Gotelli, whose husband worked at the vineyard, has picked up about 200
over 20 years.

"I started picking them up during hikes," said Gotelli. "Now they're the
reasons for taking walks. Once I started picking them up, I just continued
to do it. They're not attractive, but they're different."

Erickson, who is semi-retired but serves as the geology department
chairman,
searches at least once a week. The best time is after a light rain, which
highlights their color and distinguishes them from similar-looking
pebbles. Also involved in the project are Steve Norwick, professor of
environmental studies and planning, and Diane O'Connor, a graduate
student at UC Berkeley and Erickson's former student.

The group is concentrating on areas where sediments can be dated to the
Pliocene Epoch. Outside Dry Creek Valley, they have had the most success
at Putah Creek near Davis. They have found four samples there.

There is no consensus on how tektites form, but a common belief is that
they were vaporized meteorite particles that were blasted back beyond the
earth's atmosphere upon the meteorite's impact. They cooled, plummeted
back into the atmosphere and distributed into a strewn field.

Erickson says two factors support his tektite hypothesis. The first is
appearance. His samples share physical characteristics with tektites found
in the strewn fields of the Czech Republic, Australia, Indochina, the Gold
Coast of Africa and southeastern United States (from Georgia to Texas).
They look like spheres of dusty black glass, marked throughout with
shallow pits separated by thin boundaries. Deep grooves cut across some of
them.

The second part of his hypothesis cites the distance between the discovery
sites of the samples. Dry Creek Valley and Putah Creek are about 80 miles
apart, possibly significant since strewn fields cover large areas.

Erickson believes the samples were formed in the respective areas where
they were found, and not transported by an ancient stream that might have
flowed between the two locations. He says stream transport would have
rounded and reshaped their surface.

"One reason we believe these are tektites is there is little weathering," said
Norwick, who teaches soil science classes. "The natural glasses of our
region aren't glass anymore after 3 million years."

There are enough differences between the samples and proven tektites to
discount Erickson's hypothesis. The samples register higher magnetic and
water content. Compared with lava rock, however, those contents are
relatively low.

Erickson estimates he has spent about $1,000 on the project. Tests range in
price from $150 to $400. He also accounts for gas and upkeep of his truck.

"I tell my friends I'm supported by the 'Erickson Foundation,' " he said.

For now, Erickson and his project partners will continue their search for
samples, focusing in on 100-mile areas around Dry Creek Valley and Putah
Creek.

More tests on samples are to follow.

Erickson is enlisting the help of local gem and mineral clubs, vineyard
workers and others who might know of the existence of more samples. And
if no one knows what he is talking about, Erickson simply pulls the
"tektite" from his pocket.

Even if the samples turn out to be something other than tektites, Erickson
is excited about the possibility of a discovery.

"It could be tektite or some odd kind of pebble, something that's never been
seen," he said.
Received on Mon 02 Jun 2003 11:54:25 AM PDT