SACRAMENTO, Calif. — After serving nearly 30 years as a doorstop for a nuclear physicist, a hunk of petrified wood from Arizona has finally been recognized as a one-of-a-kind find. The 210-million-year-old piece of wood contains the first fossilized fire scar ever discovered, researchers reported here this week at the Ecological Society of America's annual meeting.
Evidence for ancient forest fires predates the dinosaurs, but the clues come from charcoal, not from marks on fossilized trees. Charcoal remains of Earth's oldest fires date back more than 400 million years. No one has ever spotted a fire scar on petrified wood before, said lead study author Bruce Byers, a natural resources consultant from Falls Church, Virginia. That's because the scientists who study petrified wood rarely cross paths with forest fire researchers, Byers suspects. But Byers thinks more fossil fire scars will be found.
"Seeing patterns in nature probably requires a mental search image for those patterns," Byers said. "Disciplinary divisions may be a barrier for sharing those patterns, but I think if people start looking, they will see those patterns." [See Photos of the First Fire-Scarred Petrified Wood]
Byers spent two decades staring at his father's 16-pound (7 kilograms) doorstop before realizing it might be from a fire-scarred tree. His father, Cleo Byers, was a nuclear physicist for Los Alamos National Laboratory in New Mexico, and took his children on hikes throughout the Southwest, Bruce Byers said. The rosy-pink stone came home with father and son 28 years ago, after a hiking trip near Utah's Bears Ears Buttes. The colorful chunk was collected on national forest land, where it's legal to take petrified wood, according to Byers, who has detailed the story on his blog. The petrified chunk likely came from the Chinle Formation, the same wood-rich rock layer that litters Arizona's Petrified Forest National Park with huge, crystallized trees. [Photos of Arizona's Amazing Petrified Forest]
Decades later, Bruce Byers took on a contract to help fire ecology researchers in Colorado's Front Range.
"I learned to recognize the distinctive patterns of modern fire scars, and I learned how important fire scars are in reconstructing the fire history of modern forests," Byers recalls.
Afterward, on Byers' next visit to his parents' New Mexico home, the telltale signs of a fire scar jumped out from the familiar piece of petrified wood.
A fire-wounded tree valiantly tries to heal itself. The surviving wood hugs the fire scar, growing back over the raw, burned inner wood. The healing curls of wood leave a unique pattern of growth rays as they stretch around the trunk.