News Column

Desert Bones, Scattered Clues to Climate Change

Nov. 19, 2012

Henry Brean

climate change

Retired schoolteacher Pat Weidknecht hunched over in the sun, plucking small bits of old bone from a rocky patch of desert at the valley's northwestern edge.

The ground was littered with the fossilized fragments of mammoths, horses and camels, so Weidknecht spent hours on her hands and knees, gathering up the pieces like an ice age crime scene investigator.

Some of the splintered bones were as big as a hand. Most were smaller than a finger and resembled chunks of plastic pipe or plain old rocks.

Weidknecht picked them up one by one and dropped them in a plastic sandwich bag.

The work was hot, tedious and sometimes uncomfortable, and she couldn't have been happier about it.

"The fact that I held something in my hand that is anywhere from 10,000 to 60,000 or 70,000 years old - something that was living, something that used to roam out here - that's cool. That's just cool," she said as she kneeled on a throw pillow at the edge of a dig site in the Upper Las Vegas Wash.

Weidknecht is part of a small army of volunteers recruited to keep an eye on the fossil-rich swath of federal land where researchers are trying to unlock the mysteries of climate change and mass extinction at the end of the last ice age. More than 75 valley residents have been trained as site stewards by the U.S. Bureau of Land Management and its research partners from the San Bernardino County Museum in California.

Each steward is assigned a 1-square-mile area to check on at least four times a year for signs of human disturbance or new evidence of fossils emerging from the ground at previous dig sites, a process known as "cyclic prospecting."

The job is part security guard, part "citizen scientist," according to geologist and paleontologist Kathleen Springer, who leads the San Bernardino County Museum's work in the Upper Las Vegas Wash.

"There's potential for stuff to be eroding out of here for thousands of years," Springer said. Without the site stewards, it would be almost impossible for researchers like her to check and recheck roughly 500 fossil sites scattered across more than 13,000 acres, she said.

As a reward for the stewards, Springer and company took them along on a dig early this month. The event was held with the 50th anniversary of the "Big Dig" at Tule Springs, a 1962 operation that featured the first large-scale use of radiocarbon dating.

Over three days, the site stewards helped collect fossils at three areas near the wash.

One site yielded so much mammoth bone scattered at the surface that the team didn't have time to dig down to see what might be hiding underneath. The two other sites offered a few more mammoth bones and the fossilized remains of other long-extinct mammals.

A few feet from where Weidknecht was kneeling in the dirt, they collected the jawbones of two ice age horses and several large rib bones lined up roughly the way they would have been inside the mammoth that once carried them.

They also recovered the specimen that brought the site to Springer's attention to begin with: a football-sized mammoth tooth eroding in plain sight at the base of a creosote bush.

For Weidknecht, it was an eye-opening look at a part of the valley she was familiar with for other reasons. When she taught history and government classes at Shadow Ridge High School, she also

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